<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019b0123-fed9-78e8-85d0-338342813f92,g:355bb63a-5317-4cac-9459-fe6171cb9873-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://telixpharma.com/role/Cover" xlink:type="simple" xlink:href="tlx-20251231.xsd#Cover"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019b352d-ac18-71fc-9ee2-92db14a228bf" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentInformationTable_019b352d-ac18-71fc-9ee2-92db14a228bf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesAddressTypeAxis_019b352d-ac18-786f-8cf4-2916920f6aa2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressesAddressTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_019b352d-ac18-71fc-9ee2-92db14a228bf" xlink:to="loc_dei_EntityAddressesAddressTypeAxis_019b352d-ac18-786f-8cf4-2916920f6aa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019b352d-ac18-786f-8cf4-2916920f6aa2_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019b352d-ac18-786f-8cf4-2916920f6aa2" xlink:to="loc_dei_AddressTypeDomain_019b352d-ac18-786f-8cf4-2916920f6aa2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019b352d-ac18-78bd-88bf-e3f1de2c9623" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019b352d-ac18-786f-8cf4-2916920f6aa2" xlink:to="loc_dei_AddressTypeDomain_019b352d-ac18-78bd-88bf-e3f1de2c9623" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_BusinessContactMember_019b352d-ac18-7c5f-ac89-f7cbb5f11e72" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_BusinessContactMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_AddressTypeDomain_019b352d-ac18-78bd-88bf-e3f1de2c9623" xlink:to="loc_dei_BusinessContactMember_019b352d-ac18-7c5f-ac89-f7cbb5f11e72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019b352d-ac18-7aa2-8488-75650df4dae8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentType_019b352d-ac18-7aa2-8488-75650df4dae8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentRegistrationStatement_019b352d-ac18-7ead-9e53-0a6bc482fcb7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentRegistrationStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentRegistrationStatement_019b352d-ac18-7ead-9e53-0a6bc482fcb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport_019b352d-ac18-7083-9954-c8f0c0b0f470" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentAnnualReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentAnnualReport_019b352d-ac18-7083-9954-c8f0c0b0f470" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019b352d-ac18-7dcb-acd5-f0cf7c14c070" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentPeriodEndDate_019b352d-ac18-7dcb-acd5-f0cf7c14c070" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019b352d-ac18-78af-9653-be5aa2e53336" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_CurrentFiscalYearEndDate_019b352d-ac18-78af-9653-be5aa2e53336" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019b352d-ac18-7661-a310-99f19d5857af" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentTransitionReport_019b352d-ac18-7661-a310-99f19d5857af" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentShellCompanyReport_019b352d-ac18-7c80-af62-4674bb280963" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentShellCompanyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentShellCompanyReport_019b352d-ac18-7c80-af62-4674bb280963" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019b352d-ac18-7fd2-8473-71fc18de6075" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityFileNumber_019b352d-ac18-7fd2-8473-71fc18de6075" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019b352d-ac18-76a2-a413-e51a4de516d3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityRegistrantName_019b352d-ac18-76a2-a413-e51a4de516d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019b352d-ac18-757d-8c36-0493d7e4f716" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019b352d-ac18-757d-8c36-0493d7e4f716" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019b352d-ac18-749e-b0b0-f580cbe5ff99" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityAddressAddressLine1_019b352d-ac18-749e-b0b0-f580cbe5ff99" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019b352d-ac18-7a88-9162-aa4c6fdbc5d5" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityAddressCityOrTown_019b352d-ac18-7a88-9162-aa4c6fdbc5d5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCountry_019b352d-ac18-737e-afe3-1c4636a740ee" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCountry"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityAddressCountry_019b352d-ac18-737e-afe3-1c4636a740ee" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019b352d-ac18-7b0c-909b-fcea6427bfe6" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityAddressPostalZipCode_019b352d-ac18-7b0c-909b-fcea6427bfe6" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_ContactPersonnelName_019b352d-ac18-74c4-b604-67da9c24e7a1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_ContactPersonnelName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_ContactPersonnelName_019b352d-ac18-74c4-b604-67da9c24e7a1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019b352d-ac18-70ce-9e58-cb474e8536b9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_CityAreaCode_019b352d-ac18-70ce-9e58-cb474e8536b9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019b352d-ac18-7877-b43e-582515110e7a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_LocalPhoneNumber_019b352d-ac18-7877-b43e-582515110e7a" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019b352d-ac18-72ef-8555-e3845dbff2c8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_Security12bTitle_019b352d-ac18-72ef-8555-e3845dbff2c8" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019b352d-ac18-7361-bb61-0c20e6a279cd" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_TradingSymbol_019b352d-ac18-7361-bb61-0c20e6a279cd" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019b352d-ac18-779a-912a-0311c23f4fd1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_SecurityExchangeName_019b352d-ac18-779a-912a-0311c23f4fd1" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019b352d-ac18-73e7-a2ea-9d752ae213b6" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019b352d-ac18-73e7-a2ea-9d752ae213b6" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_019b352d-ac18-7a8a-b141-8ea7f7589fcf" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityWellKnownSeasonedIssuer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_019b352d-ac18-7a8a-b141-8ea7f7589fcf" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers_019b352d-ac18-77d5-9473-d46a84a385f8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityVoluntaryFilers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityVoluntaryFilers_019b352d-ac18-77d5-9473-d46a84a385f8" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019b352d-ac18-7ac3-bfc3-25ee3b6af625" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityCurrentReportingStatus_019b352d-ac18-7ac3-bfc3-25ee3b6af625" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019b352d-ac18-7803-87fd-a80b8d0670e9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityInteractiveDataCurrent_019b352d-ac18-7803-87fd-a80b8d0670e9" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019b352d-ac18-7562-84b6-f68cd8a5f1e2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityFilerCategory_019b352d-ac18-7562-84b6-f68cd8a5f1e2" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019b352d-ac18-749a-a47b-3b612a05cec0" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityEmergingGrowthCompany_019b352d-ac18-749a-a47b-3b612a05cec0" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_IcfrAuditorAttestationFlag_019b352d-ac18-7716-8268-3dc9e24866c1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_IcfrAuditorAttestationFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_IcfrAuditorAttestationFlag_019b352d-ac18-7716-8268-3dc9e24866c1" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFinStmtErrorCorrectionFlag_019b352d-ac18-769f-8bfb-97c627f5d66c" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFinStmtErrorCorrectionFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentFinStmtErrorCorrectionFlag_019b352d-ac18-769f-8bfb-97c627f5d66c" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAccountingStandard_019b352d-ac18-72fd-9976-8de9cd0d5331" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentAccountingStandard"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentAccountingStandard_019b352d-ac18-72fd-9976-8de9cd0d5331" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019b352d-ac18-71a5-b176-fc4fc44f44ad" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityShellCompany_019b352d-ac18-71a5-b176-fc4fc44f44ad" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019b352d-ac18-71f7-b877-93a1b5b1ae9d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_EntityCentralIndexKey_019b352d-ac18-71f7-b877-93a1b5b1ae9d" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019b352d-ac18-70c3-a561-0aa215cc46f7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentFiscalYearFocus_019b352d-ac18-70c3-a561-0aa215cc46f7" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019b352d-ac18-763a-a03f-3b8149ba2914" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019b352d-ac18-763a-a03f-3b8149ba2914" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019b352d-ac18-7821-ae05-bd0eaca2e0ae" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019b352d-ac18-766e-90a7-a1961abf7b96" xlink:to="loc_dei_AmendmentFlag_019b352d-ac18-7821-ae05-bd0eaca2e0ae" xlink:type="arc" order="34"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/Consolidatedstatementofchangesinequity" xlink:type="simple" xlink:href="tlx-20251231.xsd#Consolidatedstatementofchangesinequity"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/Consolidatedstatementofchangesinequity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_StatementOfChangesInEquityLineItems_019b0124-0383-7b14-9e95-77703f684b77" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_StatementOfChangesInEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_StatementOfChangesInEquityTable_019b0124-0383-7ec0-aeba-485a391edc2a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_StatementOfChangesInEquityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_StatementOfChangesInEquityLineItems_019b0124-0383-7b14-9e95-77703f684b77" xlink:to="loc_ifrs-full_StatementOfChangesInEquityTable_019b0124-0383-7ec0-aeba-485a391edc2a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-0383-703c-a40f-efcd0b7e743f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_StatementOfChangesInEquityTable_019b0124-0383-7ec0-aeba-485a391edc2a" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-0383-703c-a40f-efcd0b7e743f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-703c-a40f-efcd0b7e743f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-0383-703c-a40f-efcd0b7e743f" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-703c-a40f-efcd0b7e743f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-0383-703c-a40f-efcd0b7e743f" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapitalMember_019b0124-0383-7dee-aff8-c75ea35ec1d6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:to="loc_ifrs-full_IssuedCapitalMember_019b0124-0383-7dee-aff8-c75ea35ec1d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CapitalReserveMember_019b0124-0383-79cb-b072-aa4333b14501" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CapitalReserveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:to="loc_ifrs-full_CapitalReserveMember_019b0124-0383-79cb-b072-aa4333b14501" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherReservesMember_019b0124-0383-7b13-a944-a636f030a88d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:to="loc_ifrs-full_OtherReservesMember_019b0124-0383-7b13-a944-a636f030a88d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RetainedEarningsMember_019b0124-0383-7b7b-b3b2-e2293c745bed" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-0383-737e-99fd-e91003274489" xlink:to="loc_ifrs-full_RetainedEarningsMember_019b0124-0383-7b7b-b3b2-e2293c745bed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ChangesInEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_StatementOfChangesInEquityLineItems_019b0124-0383-7b14-9e95-77703f684b77" xlink:to="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019b0124-0383-71f5-95d5-b72954e74f0b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_Equity_019b0124-0383-71f5-95d5-b72954e74f0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLoss_019b0124-0383-73bb-a8e9-22a695c4678e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_ProfitLoss_019b0124-0383-73bb-a8e9-22a695c4678e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherComprehensiveIncome_019b0124-04a2-7bcb-ad24-9038c00a6409" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_OtherComprehensiveIncome_019b0124-04a2-7bcb-ad24-9038c00a6409" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComprehensiveIncome_019b0124-04a2-7a1c-a922-61c62ef526a7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_ComprehensiveIncome_019b0124-04a2-7a1c-a922-61c62ef526a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssueOfEquity_019b0124-04a2-762b-a2ce-1152959ab2f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssueOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_IssueOfEquity_019b0124-04a2-762b-a2ce-1152959ab2f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughExerciseOfOptions_019b0124-04a2-7cff-91f4-c754b6fafa3e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughExerciseOfOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughExerciseOfOptions_019b0124-04a2-7cff-91f4-c754b6fafa3e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssueOfConvertibleInstruments_019b0124-04a2-7bc9-93c1-ba2f8ecf9c23" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssueOfConvertibleInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_IssueOfConvertibleInstruments_019b0124-04a2-7bc9-93c1-ba2f8ecf9c23" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue_019b0124-04a2-74d3-a424-93f140963d13" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue_019b0124-04a2-74d3-a424-93f140963d13" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions_019b0124-04a2-7aa1-a6bb-0c46f77beb56" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions_019b0124-04a2-7aa1-a6bb-0c46f77beb56" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity_019b0124-04a2-7578-9eeb-08326ecb997a" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity_019b0124-04a2-7578-9eeb-08326ecb997a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRights_019b35bb-86fb-7870-bf5b-9f68b28d907b" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRights_019b35bb-86fb-7870-bf5b-9f68b28d907b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity_019b0124-04a2-7e71-9735-95370da3448c" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity_019b0124-04a2-7e71-9735-95370da3448c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ChangesInEquity_019b0124-04a2-7720-9d14-dfe88382a95f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ChangesInEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ChangesInEquityAbstract_019b0124-0383-7c51-9ba3-007eb178c60e" xlink:to="loc_ifrs-full_ChangesInEquity_019b0124-04a2-7720-9d14-dfe88382a95f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019b0124-04a2-7723-a4aa-bbb40a7ca7f5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/MaterialaccountingpolicyinformationPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#MaterialaccountingpolicyinformationPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/MaterialaccountingpolicyinformationPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a2-7841-808d-4a144e7f086d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a2-7c88-98db-52055b85f9ad" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a2-7841-808d-4a144e7f086d" xlink:to="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a2-7c88-98db-52055b85f9ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a2-77d8-8fbe-32dc2df69f7b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a2-7c88-98db-52055b85f9ad" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a2-77d8-8fbe-32dc2df69f7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-77d8-8fbe-32dc2df69f7b_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a2-77d8-8fbe-32dc2df69f7b" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-77d8-8fbe-32dc2df69f7b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a2-77d8-8fbe-32dc2df69f7b" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BuildingsMember_019b0124-04a2-7b2e-8613-db149bd504c3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BuildingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:to="loc_ifrs-full_BuildingsMember_019b0124-04a2-7b2e-8613-db149bd504c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PlantAndEquipmentMember_019bfc7b-5832-78e7-87d5-dbe19013d777" xlink:href="tlx-20251231.xsd#tlx_PlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:to="loc_tlx_PlantAndEquipmentMember_019bfc7b-5832-78e7-87d5-dbe19013d777" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FixturesAndFittingsMember_019b0124-04a2-765e-902c-2553fa973101" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FixturesAndFittingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:to="loc_ifrs-full_FixturesAndFittingsMember_019b0124-04a2-765e-902c-2553fa973101" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LeasedPlantAndEquipmentMember_019b0124-04a2-7bce-ad85-b089c58e4dcb" xlink:href="tlx-20251231.xsd#tlx_LeasedPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a2-7884-a573-9162353dea45" xlink:to="loc_tlx_LeasedPlantAndEquipmentMember_019b0124-04a2-7bce-ad85-b089c58e4dcb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeAxis_019b0124-04a2-79e5-800e-cc30f0877d0d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a2-7c88-98db-52055b85f9ad" xlink:to="loc_ifrs-full_RangeAxis_019b0124-04a2-79e5-800e-cc30f0877d0d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-79e5-800e-cc30f0877d0d_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-79e5-800e-cc30f0877d0d" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-79e5-800e-cc30f0877d0d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-73a4-baa1-6a774f92b139" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-79e5-800e-cc30f0877d0d" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-73a4-baa1-6a774f92b139" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-7056-b2ae-3570775ecf27" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BottomOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-73a4-baa1-6a774f92b139" xlink:to="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-7056-b2ae-3570775ecf27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-700c-8d18-799796bc0f47" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TopOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-73a4-baa1-6a774f92b139" xlink:to="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-700c-8d18-799796bc0f47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimePropertyPlantAndEquipment_019b0124-04a2-7a47-aad3-704aea5e9383" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UsefulLifeMeasuredAsPeriodOfTimePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a2-7841-808d-4a144e7f086d" xlink:to="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimePropertyPlantAndEquipment_019b0124-04a2-7a47-aad3-704aea5e9383" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/MaterialaccountingpolicyinformationIntangibleAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#MaterialaccountingpolicyinformationIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/MaterialaccountingpolicyinformationIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a2-71f2-ab4b-58f37133face" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a2-7f04-a97b-eaf033c11f56" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a2-71f2-ab4b-58f37133face" xlink:to="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a2-7f04-a97b-eaf033c11f56" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a2-7f04-a97b-eaf033c11f56" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-762e-a97a-03ccabcf5925" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a2-7c78-b4f6-9fbfb9c7c1b2" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-762e-a97a-03ccabcf5925" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PatentsTrademarksLicensesAndCustomerContractsMember_019b0124-04a2-716d-b532-0aeb9ce7468c" xlink:href="tlx-20251231.xsd#tlx_PatentsTrademarksLicensesAndCustomerContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-762e-a97a-03ccabcf5925" xlink:to="loc_tlx_PatentsTrademarksLicensesAndCustomerContractsMember_019b0124-04a2-716d-b532-0aeb9ce7468c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntellectualPropertiesMember_019b0124-04a2-7fc3-b4d1-f1892d7d9115" xlink:href="tlx-20251231.xsd#tlx_IntellectualPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a2-762e-a97a-03ccabcf5925" xlink:to="loc_tlx_IntellectualPropertiesMember_019b0124-04a2-7fc3-b4d1-f1892d7d9115" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeAxis_019b0124-04a2-7837-8891-025cc858bab3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a2-7f04-a97b-eaf033c11f56" xlink:to="loc_ifrs-full_RangeAxis_019b0124-04a2-7837-8891-025cc858bab3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-7837-8891-025cc858bab3_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-7837-8891-025cc858bab3" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-7837-8891-025cc858bab3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-7fb1-be67-78983b10f1b4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-7837-8891-025cc858bab3" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-7fb1-be67-78983b10f1b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-786f-9091-c42096f75a82" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BottomOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-7fb1-be67-78983b10f1b4" xlink:to="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-786f-9091-c42096f75a82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-78a7-8909-af1bf91ff21e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TopOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-7fb1-be67-78983b10f1b4" xlink:to="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-78a7-8909-af1bf91ff21e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill_019b0124-04a2-78b7-b06b-bfcc00189c36" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a2-71f2-ab4b-58f37133face" xlink:to="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill_019b0124-04a2-78b7-b06b-bfcc00189c36" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/MaterialaccountingpolicyinformationRevenueDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#MaterialaccountingpolicyinformationRevenueDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/MaterialaccountingpolicyinformationRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-75d9-91ac-a6d9bef952fa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-7f9a-a1cb-e6a95fc39b29" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-75d9-91ac-a6d9bef952fa" xlink:to="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-7f9a-a1cb-e6a95fc39b29" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeAxis_019b0124-04a2-72a5-bdf1-c974bab81a76" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-7f9a-a1cb-e6a95fc39b29" xlink:to="loc_ifrs-full_RangeAxis_019b0124-04a2-72a5-bdf1-c974bab81a76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-72a5-bdf1-c974bab81a76_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-72a5-bdf1-c974bab81a76" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-72a5-bdf1-c974bab81a76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-04a2-70c5-93c1-efee1c9f1a7f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_RangeAxis_019b0124-04a2-72a5-bdf1-c974bab81a76" xlink:to="loc_ifrs-full_RangeDomain_019b0124-04a2-70c5-93c1-efee1c9f1a7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-74ac-8d67-e37a56c2f143" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BottomOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-70c5-93c1-efee1c9f1a7f" xlink:to="loc_ifrs-full_BottomOfRangeMember_019b0124-04a2-74ac-8d67-e37a56c2f143" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-7dcb-bc80-1b2abf3c18ba" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TopOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-04a2-70c5-93c1-efee1c9f1a7f" xlink:to="loc_ifrs-full_TopOfRangeMember_019b0124-04a2-7dcb-bc80-1b2abf3c18ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SalesOfGoodsCreditTerm_019b0124-04a2-744c-b6d2-c633182a9e3c" xlink:href="tlx-20251231.xsd#tlx_SalesOfGoodsCreditTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-75d9-91ac-a6d9bef952fa" xlink:to="loc_tlx_SalesOfGoodsCreditTerm_019b0124-04a2-744c-b6d2-c633182a9e3c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SegmentreportingScheduleofSegmentPerformanceDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SegmentreportingScheduleofSegmentPerformanceDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SegmentreportingScheduleofSegmentPerformanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7ee6-b24a-e55d6d02174d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7ee6-b24a-e55d6d02174d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7655-b477-cadf10575e5c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7ee6-b24a-e55d6d02174d" xlink:to="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7655-b477-cadf10575e5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7655-b477-cadf10575e5c_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7655-b477-cadf10575e5c" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7655-b477-cadf10575e5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7ebe-88c1-6e1f4e7f55aa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7655-b477-cadf10575e5c" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7ebe-88c1-6e1f4e7f55aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OperatingSegmentsMember_019b0124-04a2-7a8c-bef2-1bd46c6723f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7ebe-88c1-6e1f4e7f55aa" xlink:to="loc_ifrs-full_OperatingSegmentsMember_019b0124-04a2-7a8c-bef2-1bd46c6723f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EliminationOfIntersegmentAmountsMember_019b39ac-49ec-79a4-8545-746fa12db144" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EliminationOfIntersegmentAmountsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7ebe-88c1-6e1f4e7f55aa" xlink:to="loc_ifrs-full_EliminationOfIntersegmentAmountsMember_019b39ac-49ec-79a4-8545-746fa12db144" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7121-8391-304aa009fe00" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7ee6-b24a-e55d6d02174d" xlink:to="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7121-8391-304aa009fe00" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7121-8391-304aa009fe00_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7121-8391-304aa009fe00" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7121-8391-304aa009fe00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7c15-a763-741898ea4500" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7121-8391-304aa009fe00" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7c15-a763-741898ea4500" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PrecisionMedicineMember_019b0124-04a2-79da-b90f-a29d861f0857" xlink:href="tlx-20251231.xsd#tlx_PrecisionMedicineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7c15-a763-741898ea4500" xlink:to="loc_tlx_PrecisionMedicineMember_019b0124-04a2-79da-b90f-a29d861f0857" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeuticsMember_019b0124-04a2-7176-9022-f2fdc15aeff0" xlink:href="tlx-20251231.xsd#tlx_TherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7c15-a763-741898ea4500" xlink:to="loc_tlx_TherapeuticsMember_019b0124-04a2-7176-9022-f2fdc15aeff0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7263-b491-7f1275fb9cc3" xlink:href="tlx-20251231.xsd#tlx_ManufacturingSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7c15-a763-741898ea4500" xlink:to="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7263-b491-7f1275fb9cc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromContractsWithCustomers_019b0124-04a2-7d4b-8944-9801aa1c20b8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromContractsWithCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_RevenueFromContractsWithCustomers_019b0124-04a2-7d4b-8944-9801aa1c20b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InterSegmentRevenue_019b39e6-7353-7893-aeb8-11f989517642" xlink:href="tlx-20251231.xsd#tlx_InterSegmentRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_tlx_InterSegmentRevenue_019b39e6-7353-7893-aeb8-11f989517642" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CostOfSales_019b0124-04a2-7669-8ce0-b459398255da" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CostOfSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_CostOfSales_019b0124-04a2-7669-8ce0-b459398255da" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossProfit_019b0124-04a2-71ab-b6b1-a89200464404" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_GrossProfit_019b0124-04a2-71ab-b6b1-a89200464404" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ResearchAndDevelopmentExpense_019b0124-04a2-7f1a-b0bb-bcf33ab19d06" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_ResearchAndDevelopmentExpense_019b0124-04a2-7f1a-b0bb-bcf33ab19d06" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SalesAndMarketingExpense_019b0124-04a2-76a6-95d9-cf00f36ad100" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SalesAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_SalesAndMarketingExpense_019b0124-04a2-76a6-95d9-cf00f36ad100" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingAndDistributionCosts_019b0124-04a2-7c17-aa2c-e71326105d00" xlink:href="tlx-20251231.xsd#tlx_ManufacturingAndDistributionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_tlx_ManufacturingAndDistributionCosts_019b0124-04a2-7c17-aa2c-e71326105d00" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeneralAndAdministrativeExpense_019b0124-04a2-7b0b-8856-4a46685fc99e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_GeneralAndAdministrativeExpense_019b0124-04a2-7b0b-8856-4a46685fc99e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherGainsLosses_019b0124-04a2-7d58-a7fb-ec21b33823ba" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_OtherGainsLosses_019b0124-04a2-7d58-a7fb-ec21b33823ba" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossFromOperatingActivities_019b0124-04a2-73bf-888a-fab0165e6076" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossFromOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_ProfitLossFromOperatingActivities_019b0124-04a2-73bf-888a-fab0165e6076" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherGainsLosses_019bfc84-25f1-7647-9e6a-414da060a555" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherGainsLosses"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DepreciationAndAmortisationExpense_019b0124-04a2-7821-826e-afc761673cc0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DepreciationAndAmortisationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_ifrs-full_DepreciationAndAmortisationExpense_019b0124-04a2-7821-826e-afc761673cc0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization_019b0124-04a2-77a6-902d-9dbbb0ed4128" xlink:href="tlx-20251231.xsd#tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7953-b0da-807cff15f64b" xlink:to="loc_tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization_019b0124-04a2-77a6-902d-9dbbb0ed4128" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SegmentreportingScheduleofReconciliationofSegmentAdjustedEBITDAtoProfitLossBeforeIncomeTaxesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SegmentreportingScheduleofReconciliationofSegmentAdjustedEBITDAtoProfitLossBeforeIncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SegmentreportingScheduleofReconciliationofSegmentAdjustedEBITDAtoProfitLossBeforeIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-719b-b2c3-84f806b045bd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7921-9d93-1ff3a15def5f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-719b-b2c3-84f806b045bd" xlink:to="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7921-9d93-1ff3a15def5f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-7921-9d93-1ff3a15def5f" xlink:to="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7898-9325-5a6167a1df72" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7e7a-8ac5-9ae85d6d6ae0" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7898-9325-5a6167a1df72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnallocatedAmountsMember_019b0124-04a2-798a-9c96-51f070c25215" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnallocatedAmountsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7898-9325-5a6167a1df72" xlink:to="loc_ifrs-full_UnallocatedAmountsMember_019b0124-04a2-798a-9c96-51f070c25215" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract_019b0124-04a2-7e39-81a7-b1e60efddd02" xlink:href="tlx-20251231.xsd#tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-719b-b2c3-84f806b045bd" xlink:to="loc_tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract_019b0124-04a2-7e39-81a7-b1e60efddd02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization_019b0124-04a2-705b-90a1-6a0808a154c1" xlink:href="tlx-20251231.xsd#tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract_019b0124-04a2-7e39-81a7-b1e60efddd02" xlink:to="loc_tlx_AdjustedEarningsLossBeforeInterestTaxDepreciationAndAmortization_019b0124-04a2-705b-90a1-6a0808a154c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:href="tlx-20251231.xsd#tlx_UnallocatedIncomeExpensesAndEliminationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract_019b0124-04a2-7e39-81a7-b1e60efddd02" xlink:to="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeneralAndAdministrativeExpense_019b0124-04a2-7442-9d27-f7ad08f89c5c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:to="loc_ifrs-full_GeneralAndAdministrativeExpense_019b0124-04a2-7442-9d27-f7ad08f89c5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherGainsLosses_019b0124-04a2-7e41-9e1d-231d453e9b01" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:to="loc_ifrs-full_OtherGainsLosses_019b0124-04a2-7e41-9e1d-231d453e9b01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinanceIncome_019be8d7-5993-710b-b55e-a7cabe3a333e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinanceIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:to="loc_ifrs-full_FinanceIncome_019be8d7-5993-710b-b55e-a7cabe3a333e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinanceCosts_019b0124-04a2-73d6-a144-137ecd7e1df5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:to="loc_ifrs-full_FinanceCosts_019b0124-04a2-73d6-a144-137ecd7e1df5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DepreciationAndAmortisationExpense_019b0124-04a2-7be1-bfa7-7c969459e07d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DepreciationAndAmortisationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_UnallocatedIncomeExpensesAndEliminationsAbstract_019b0124-04a2-7f7f-85ef-c0df59f76e1b" xlink:to="loc_ifrs-full_DepreciationAndAmortisationExpense_019b0124-04a2-7be1-bfa7-7c969459e07d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossBeforeTax_019b0124-04a2-769b-b067-f23d8c8c4ccc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ReconciliationOfTotalSegmentAdjustedEBITDAAndGroupAdjustedEBITAToProfitLossBeforeIncomeTaxAbstract_019b0124-04a2-7e39-81a7-b1e60efddd02" xlink:to="loc_ifrs-full_ProfitLossBeforeTax_019b0124-04a2-769b-b067-f23d8c8c4ccc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SegmentreportingNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SegmentreportingNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SegmentreportingNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b3a01-aa69-7b8e-8e5b-564df8fac0b7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b3a01-aa69-7b8e-8e5b-564df8fac0b7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsAxis_019b3a02-2d49-7341-883c-774ab5114e8d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b3a01-aa69-7b8e-8e5b-564df8fac0b7" xlink:to="loc_ifrs-full_SegmentConsolidationItemsAxis_019b3a02-2d49-7341-883c-774ab5114e8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d49-7341-883c-774ab5114e8d_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b3a02-2d49-7341-883c-774ab5114e8d" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d49-7341-883c-774ab5114e8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d4a-7d43-8b17-1f9c73ad3ac0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b3a02-2d49-7341-883c-774ab5114e8d" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d4a-7d43-8b17-1f9c73ad3ac0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnallocatedAmountsMember_019b3a02-48b2-7183-8e2f-9c969c1265d9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnallocatedAmountsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d4a-7d43-8b17-1f9c73ad3ac0" xlink:to="loc_ifrs-full_UnallocatedAmountsMember_019b3a02-48b2-7183-8e2f-9c969c1265d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaterialReconcilingItemsMember_019be8e1-a54e-7b87-be7c-48d0bc89c6ec" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b3a02-2d4a-7d43-8b17-1f9c73ad3ac0" xlink:to="loc_ifrs-full_MaterialReconcilingItemsMember_019be8e1-a54e-7b87-be7c-48d0bc89c6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EmployeeBenefitsExpense_019b39f0-cbe0-75b7-9c18-13aba8ae70bf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EmployeeBenefitsExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_EmployeeBenefitsExpense_019b39f0-cbe0-75b7-9c18-13aba8ae70bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashAndCashEquivalents_019b0124-04a2-7442-8b41-115d70b8fba1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_CashAndCashEquivalents_019b0124-04a2-7442-8b41-115d70b8fba1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentFinancialAssets_019b0124-04a2-7a60-b12b-5425962ad65e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_NoncurrentFinancialAssets_019b0124-04a2-7a60-b12b-5425962ad65e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipment_019b0124-04a2-7ae8-94df-8f47968d15fb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_PropertyPlantAndEquipment_019b0124-04a2-7ae8-94df-8f47968d15fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentPortionOfNoncurrentBondsIssued_019b0124-04a2-7620-ae11-cfd99f063cf9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentPortionOfNoncurrentBondsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b3a01-fef9-75c6-98a1-147420fe311e" xlink:to="loc_ifrs-full_NoncurrentPortionOfNoncurrentBondsIssued_019b0124-04a2-7620-ae11-cfd99f063cf9" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SegmentreportingScheduleofOperatingSegmentAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SegmentreportingScheduleofOperatingSegmentAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SegmentreportingScheduleofOperatingSegmentAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7a8a-8d56-51dceab441ca" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-726c-a477-dcdac2232976" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7a8a-8d56-51dceab441ca" xlink:to="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-726c-a477-dcdac2232976" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7226-a238-7827f87fc1c5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-726c-a477-dcdac2232976" xlink:to="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7226-a238-7827f87fc1c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7226-a238-7827f87fc1c5_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7226-a238-7827f87fc1c5" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-7226-a238-7827f87fc1c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-721f-b4ae-1f674d1682f6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019b0124-04a2-7226-a238-7827f87fc1c5" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-721f-b4ae-1f674d1682f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OperatingSegmentsMember_019b0124-04a2-7ebe-86a5-fa3a82245bcd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-721f-b4ae-1f674d1682f6" xlink:to="loc_ifrs-full_OperatingSegmentsMember_019b0124-04a2-7ebe-86a5-fa3a82245bcd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaterialReconcilingItemsMember_019b0124-04a2-7a6d-a8f6-3f2e11ab0951" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019b0124-04a2-721f-b4ae-1f674d1682f6" xlink:to="loc_ifrs-full_MaterialReconcilingItemsMember_019b0124-04a2-7a6d-a8f6-3f2e11ab0951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsAxis_019b0124-04a2-76ff-af5b-f3ad9c0cab2f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-726c-a477-dcdac2232976" xlink:to="loc_ifrs-full_SegmentsAxis_019b0124-04a2-76ff-af5b-f3ad9c0cab2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-76ff-af5b-f3ad9c0cab2f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-76ff-af5b-f3ad9c0cab2f" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-76ff-af5b-f3ad9c0cab2f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7498-bbfd-bdc70bed78b0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-76ff-af5b-f3ad9c0cab2f" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7498-bbfd-bdc70bed78b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PrecisionMedicineMember_019b0124-04a2-7a83-8f00-3c0b2c046127" xlink:href="tlx-20251231.xsd#tlx_PrecisionMedicineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7498-bbfd-bdc70bed78b0" xlink:to="loc_tlx_PrecisionMedicineMember_019b0124-04a2-7a83-8f00-3c0b2c046127" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeuticsMember_019b0124-04a2-7043-9f8c-bd4d9c365539" xlink:href="tlx-20251231.xsd#tlx_TherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7498-bbfd-bdc70bed78b0" xlink:to="loc_tlx_TherapeuticsMember_019b0124-04a2-7043-9f8c-bd4d9c365539" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7b7c-93a3-639b7ec47bfa" xlink:href="tlx-20251231.xsd#tlx_ManufacturingSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7498-bbfd-bdc70bed78b0" xlink:to="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7b7c-93a3-639b7ec47bfa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OperatingSegmentAssetsAndLiabilitiesAbstract_019b0124-04a2-7561-b02a-6da00fe724b1" xlink:href="tlx-20251231.xsd#tlx_OperatingSegmentAssetsAndLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7a8a-8d56-51dceab441ca" xlink:to="loc_tlx_OperatingSegmentAssetsAndLiabilitiesAbstract_019b0124-04a2-7561-b02a-6da00fe724b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Assets_019b0124-04a2-785f-a7b0-f41c0a6b6ef3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OperatingSegmentAssetsAndLiabilitiesAbstract_019b0124-04a2-7561-b02a-6da00fe724b1" xlink:to="loc_ifrs-full_Assets_019b0124-04a2-785f-a7b0-f41c0a6b6ef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Liabilities_019b0124-04a2-7f4a-ac01-69f9bf61ea08" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OperatingSegmentAssetsAndLiabilitiesAbstract_019b0124-04a2-7561-b02a-6da00fe724b1" xlink:to="loc_ifrs-full_Liabilities_019b0124-04a2-7f4a-ac01-69f9bf61ea08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdditionsToNoncurrentAssets_019b0124-04a2-782b-a6cc-9fc7cd47cdd6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdditionsToNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OperatingSegmentAssetsAndLiabilitiesAbstract_019b0124-04a2-7561-b02a-6da00fe724b1" xlink:to="loc_ifrs-full_AdditionsToNoncurrentAssets_019b0124-04a2-782b-a6cc-9fc7cd47cdd6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SegmentreportingScheduleofGeographicalInformationDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SegmentreportingScheduleofGeographicalInformationDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SegmentreportingScheduleofGeographicalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7da8-8e35-ef66c3c9e420" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-756c-a2dd-79579f27a548" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7da8-8e35-ef66c3c9e420" xlink:to="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-756c-a2dd-79579f27a548" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a2-7693-beca-a4bb737a31ac" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsTable_019b0124-04a2-756c-a2dd-79579f27a548" xlink:to="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a2-7693-beca-a4bb737a31ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-7693-beca-a4bb737a31ac_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a2-7693-beca-a4bb737a31ac" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-7693-beca-a4bb737a31ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a2-7693-beca-a4bb737a31ac" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_AU_019bea46-531d-7936-8520-ab48b6d71a99" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_AU"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_AU_019bea46-531d-7936-8520-ab48b6d71a99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BE_019bea46-92f8-72de-8515-e88f7c4b6fae" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_BE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_BE_019bea46-92f8-72de-8515-e88f7c4b6fae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_019b0124-04a2-7726-916c-a2fd4e6e183b" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_CA_019b0124-04a2-7726-916c-a2fd4e6e183b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019bea41-c799-7c96-9050-9e629c81b0b8" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_CN_019bea41-c799-7c96-9050-9e629c81b0b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_019bea46-c6f9-70c3-85c2-88f9622102bd" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_GB_019bea46-c6f9-70c3-85c2-88f9622102bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019b0124-04a2-721f-a232-f9f9942f5f8b" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_country_US_019b0124-04a2-721f-a232-f9f9942f5f8b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ForeignCountriesMember_019b0124-04a2-7c5c-b522-eeca80b50385" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ForeignCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a2-706e-a2cf-01d199dc80d7" xlink:to="loc_ifrs-full_ForeignCountriesMember_019b0124-04a2-7c5c-b522-eeca80b50385" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromContractsWithCustomers_019b0124-04a2-74ea-886d-665c75c4f482" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromContractsWithCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7da8-8e35-ef66c3c9e420" xlink:to="loc_ifrs-full_RevenueFromContractsWithCustomers_019b0124-04a2-74ea-886d-665c75c4f482" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentAssetsOtherThanFinancialInstrumentsDeferredTaxAssetsPostemploymentBenefitAssetsAndRightsArisingUnderInsuranceContracts_019bea45-aefa-70aa-8864-f6a01aa9096f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentAssetsOtherThanFinancialInstrumentsDeferredTaxAssetsPostemploymentBenefitAssetsAndRightsArisingUnderInsuranceContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOperatingSegmentsLineItems_019b0124-04a2-7da8-8e35-ef66c3c9e420" xlink:to="loc_ifrs-full_NoncurrentAssetsOtherThanFinancialInstrumentsDeferredTaxAssetsPostemploymentBenefitAssetsAndRightsArisingUnderInsuranceContracts_019bea45-aefa-70aa-8864-f6a01aa9096f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RevenuefromcontractswithcustomersDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RevenuefromcontractswithcustomersDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RevenuefromcontractswithcustomersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-73d4-92fc-b07b0f13d293" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-73d4-92fc-b07b0f13d293" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesAxis_019b0124-04a2-7b69-ba27-badd872c6e6f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-73d4-92fc-b07b0f13d293" xlink:to="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesAxis_019b0124-04a2-7b69-ba27-badd872c6e6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7b69-ba27-badd872c6e6f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesAxis_019b0124-04a2-7b69-ba27-badd872c6e6f" xlink:to="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7b69-ba27-badd872c6e6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7303-8e86-9946946c467c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesAxis_019b0124-04a2-7b69-ba27-badd872c6e6f" xlink:to="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7303-8e86-9946946c467c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember_019b0124-04a2-71fd-9f9a-e472f1173dfd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7303-8e86-9946946c467c" xlink:to="loc_ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember_019b0124-04a2-71fd-9f9a-e472f1173dfd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodsOrServicesTransferredOverTimeMember_019b0124-04a2-7e6b-909b-2a5180478f28" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodsOrServicesTransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TimingOfTransferOfGoodsOrServicesDomain_019b0124-04a2-7303-8e86-9946946c467c" xlink:to="loc_ifrs-full_GoodsOrServicesTransferredOverTimeMember_019b0124-04a2-7e6b-909b-2a5180478f28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7286-84c4-51f070258c64" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-04a2-73d4-92fc-b07b0f13d293" xlink:to="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7286-84c4-51f070258c64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7286-84c4-51f070258c64_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7286-84c4-51f070258c64" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7286-84c4-51f070258c64_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-71a3-a4b6-31e74a01ed02" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7286-84c4-51f070258c64" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-71a3-a4b6-31e74a01ed02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PrecisionMedicineMember_019b0124-04a2-76b6-8a39-40152da63d57" xlink:href="tlx-20251231.xsd#tlx_PrecisionMedicineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-71a3-a4b6-31e74a01ed02" xlink:to="loc_tlx_PrecisionMedicineMember_019b0124-04a2-76b6-8a39-40152da63d57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7450-8141-d0df25e80455" xlink:href="tlx-20251231.xsd#tlx_ManufacturingSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-71a3-a4b6-31e74a01ed02" xlink:to="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7450-8141-d0df25e80455" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeuticsMember_019b0124-04a2-7693-b8f0-c9cde599a9cc" xlink:href="tlx-20251231.xsd#tlx_TherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-71a3-a4b6-31e74a01ed02" xlink:to="loc_tlx_TherapeuticsMember_019b0124-04a2-7693-b8f0-c9cde599a9cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromSaleOfGoods_019b0124-04a2-7f4f-ad10-51408ac30a85" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromSaleOfGoods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_ifrs-full_RevenueFromSaleOfGoods_019b0124-04a2-7f4f-ad10-51408ac30a85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromRoyalties_019b0124-04a2-7074-af3a-27ed626b529b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_ifrs-full_RevenueFromRoyalties_019b0124-04a2-7074-af3a-27ed626b529b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromRenderingOfServices_019b0124-04a2-7aff-a476-8bbb0c51e31f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromRenderingOfServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_ifrs-full_RevenueFromRenderingOfServices_019b0124-04a2-7aff-a476-8bbb0c51e31f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RevenueFromLicensesOfIntellectualProperty_019b0124-04a2-7963-aa92-bdc127d25cee" xlink:href="tlx-20251231.xsd#tlx_RevenueFromLicensesOfIntellectualProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_tlx_RevenueFromLicensesOfIntellectualProperty_019b0124-04a2-7963-aa92-bdc127d25cee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RevenueFromResearchAndDevelopmentServices_019b0124-04a2-75ea-b868-bcdc952b696e" xlink:href="tlx-20251231.xsd#tlx_RevenueFromResearchAndDevelopmentServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_tlx_RevenueFromResearchAndDevelopmentServices_019b0124-04a2-75ea-b868-bcdc952b696e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Revenue_019b0124-04a2-742c-b43b-5da95a3ecd98" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Revenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-04a2-7705-9448-6a92c74d7ad4" xlink:to="loc_ifrs-full_Revenue_019b0124-04a2-742c-b43b-5da95a3ecd98" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ResearchanddevelopmentcostsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ResearchanddevelopmentcostsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ResearchanddevelopmentcostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfProductsAndServicesLineItems_019b0124-04a2-7573-a09c-909f42b33f2d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfProductsAndServicesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesLineItems_019b0124-04a2-7573-a09c-909f42b33f2d" xlink:to="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7a64-b827-bbcbb9f6a6f1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:to="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7a64-b827-bbcbb9f6a6f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7a64-b827-bbcbb9f6a6f1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7a64-b827-bbcbb9f6a6f1" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7a64-b827-bbcbb9f6a6f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7b62-bae8-babdee8e58f0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentsAxis_019b0124-04a2-7a64-b827-bbcbb9f6a6f1" xlink:to="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7b62-bae8-babdee8e58f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeuticsMember_019b0124-04a2-7842-be91-448482a445d3" xlink:href="tlx-20251231.xsd#tlx_TherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7b62-bae8-babdee8e58f0" xlink:to="loc_tlx_TherapeuticsMember_019b0124-04a2-7842-be91-448482a445d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PrecisionMedicineMember_019b0124-04a2-7d62-afae-f2e9fe38757c" xlink:href="tlx-20251231.xsd#tlx_PrecisionMedicineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7b62-bae8-babdee8e58f0" xlink:to="loc_tlx_PrecisionMedicineMember_019b0124-04a2-7d62-afae-f2e9fe38757c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7e6d-a18c-03cae0c3ff5b" xlink:href="tlx-20251231.xsd#tlx_ManufacturingSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019b0124-04a2-7b62-bae8-babdee8e58f0" xlink:to="loc_tlx_ManufacturingSolutionsMember_019b0124-04a2-7e6d-a18c-03cae0c3ff5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a2-7a3c-8d95-ebc50f2981ea" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:to="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a2-7a3c-8d95-ebc50f2981ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7a3c-8d95-ebc50f2981ea_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a2-7a3c-8d95-ebc50f2981ea" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7a3c-8d95-ebc50f2981ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7e91-8d62-77116127e3c3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a2-7a3c-8d95-ebc50f2981ea" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7e91-8d62-77116127e3c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:href="tlx-20251231.xsd#tlx_ProductDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7e91-8d62-77116127e3c3" xlink:to="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_Phase3Member_019bfc9d-26c1-7a59-8b11-fc03c72a163f" xlink:href="tlx-20251231.xsd#tlx_Phase3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_Phase3Member_019bfc9d-26c1-7a59-8b11-fc03c72a163f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_Phase2Member_019bfc9d-4f6d-7509-b85f-c38aaf9ceba0" xlink:href="tlx-20251231.xsd#tlx_Phase2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_Phase2Member_019bfc9d-4f6d-7509-b85f-c38aaf9ceba0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EarlyStageClinicalCandidatesMember_019bfc9d-915e-7c66-bd5e-f70c0bb2a3f5" xlink:href="tlx-20251231.xsd#tlx_EarlyStageClinicalCandidatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_EarlyStageClinicalCandidatesMember_019bfc9d-915e-7c66-bd5e-f70c0bb2a3f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CommercialMember_019bfc9e-1daf-7f50-a790-99b69aaa887d" xlink:href="tlx-20251231.xsd#tlx_CommercialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_CommercialMember_019bfc9e-1daf-7f50-a790-99b69aaa887d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PreCommercialMember_019bfc9e-5718-77b5-bf80-f4d5cbde420e" xlink:href="tlx-20251231.xsd#tlx_PreCommercialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_PreCommercialMember_019bfc9e-5718-77b5-bf80-f4d5cbde420e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PreClinicalResearchAndInnovationMember_019b0124-04a2-7f5c-bc2b-82a257b991af" xlink:href="tlx-20251231.xsd#tlx_PreClinicalResearchAndInnovationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ProductDevelopmentMember_019b0124-04a2-70fd-9755-218beb903367" xlink:to="loc_tlx_PreClinicalResearchAndInnovationMember_019b0124-04a2-7f5c-bc2b-82a257b991af" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherResearchAndDevelopmentProjectsMember_019b0124-04a2-7697-bb43-f2c865801c7d" xlink:href="tlx-20251231.xsd#tlx_OtherResearchAndDevelopmentProjectsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a2-7e91-8d62-77116127e3c3" xlink:to="loc_tlx_OtherResearchAndDevelopmentProjectsMember_019b0124-04a2-7697-bb43-f2c865801c7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsAxis_019be027-79aa-7053-ae50-c4a5865a870a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:to="loc_ifrs-full_SegmentConsolidationItemsAxis_019be027-79aa-7053-ae50-c4a5865a870a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019be027-79aa-7053-ae50-c4a5865a870a_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019be027-79aa-7053-ae50-c4a5865a870a" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019be027-79aa-7053-ae50-c4a5865a870a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentConsolidationItemsDomain_019be027-79aa-7bea-afab-4e617ed07dc9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentConsolidationItemsAxis_019be027-79aa-7053-ae50-c4a5865a870a" xlink:to="loc_ifrs-full_SegmentConsolidationItemsDomain_019be027-79aa-7bea-afab-4e617ed07dc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EliminationOfIntersegmentAmountsMember_019be027-d1dc-72f2-a7f0-b29ee5d8535d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EliminationOfIntersegmentAmountsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentConsolidationItemsDomain_019be027-79aa-7bea-afab-4e617ed07dc9" xlink:to="loc_ifrs-full_EliminationOfIntersegmentAmountsMember_019be027-d1dc-72f2-a7f0-b29ee5d8535d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryTypeAxis_019c5437-1893-758d-9266-8b2f5bc986f7" xlink:href="tlx-20251231.xsd#tlx_InventoryTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesTable_019b0124-04a2-7595-b660-17b52e2d750c" xlink:to="loc_tlx_InventoryTypeAxis_019c5437-1893-758d-9266-8b2f5bc986f7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryTypeDomain_019c5437-1893-758d-9266-8b2f5bc986f7_default" xlink:href="tlx-20251231.xsd#tlx_InventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_InventoryTypeAxis_019c5437-1893-758d-9266-8b2f5bc986f7" xlink:to="loc_tlx_InventoryTypeDomain_019c5437-1893-758d-9266-8b2f5bc986f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryTypeDomain_019c5437-1893-7f7e-869f-88a78f0f05f6" xlink:href="tlx-20251231.xsd#tlx_InventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_InventoryTypeAxis_019c5437-1893-758d-9266-8b2f5bc986f7" xlink:to="loc_tlx_InventoryTypeDomain_019c5437-1893-7f7e-869f-88a78f0f05f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ZircaixMember_019c5437-4e29-7e4e-83cb-247504bffb32" xlink:href="tlx-20251231.xsd#tlx_ZircaixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_InventoryTypeDomain_019c5437-1893-7f7e-869f-88a78f0f05f6" xlink:to="loc_tlx_ZircaixMember_019c5437-4e29-7e4e-83cb-247504bffb32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ResearchAndDevelopmentExpense_019b0124-04a2-739a-aed6-11d591503977" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfProductsAndServicesLineItems_019b0124-04a2-7573-a09c-909f42b33f2d" xlink:to="loc_ifrs-full_ResearchAndDevelopmentExpense_019b0124-04a2-739a-aed6-11d591503977" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ManufacturinganddistributioncostsScheduleofManufacturingandDistributionCostsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ManufacturinganddistributioncostsScheduleofManufacturingandDistributionCostsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ManufacturinganddistributioncostsScheduleofManufacturingandDistributionCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019b45dd-9d51-7322-9482-8f0beadf6a23" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019b45dd-9d51-71d5-893d-0f10ef476bce" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019b45dd-9d51-7322-9482-8f0beadf6a23" xlink:to="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019b45dd-9d51-71d5-893d-0f10ef476bce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019bfca1-2e8f-7a35-8a4b-cc788edb1767" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019b45dd-9d51-71d5-893d-0f10ef476bce" xlink:to="loc_srt_ProductOrServiceAxis_019bfca1-2e8f-7a35-8a4b-cc788edb1767" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7a35-8a4b-cc788edb1767_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019bfca1-2e8f-7a35-8a4b-cc788edb1767" xlink:to="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7a35-8a4b-cc788edb1767_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019bfca1-2e8f-7a35-8a4b-cc788edb1767" xlink:to="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RadiopharmacyOperationsMember_019b45dd-9d51-77ab-a382-0311bd639632" xlink:href="tlx-20251231.xsd#tlx_RadiopharmacyOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:to="loc_tlx_RadiopharmacyOperationsMember_019b45dd-9d51-77ab-a382-0311bd639632" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_QualityCostsMember_019b45dd-9d51-7775-a59c-493c16d0e8cd" xlink:href="tlx-20251231.xsd#tlx_QualityCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:to="loc_tlx_QualityCostsMember_019b45dd-9d51-7775-a59c-493c16d0e8cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SupplyChainCostsMember_019b45dd-9d51-76f9-a7d7-9386b0de758f" xlink:href="tlx-20251231.xsd#tlx_SupplyChainCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:to="loc_tlx_SupplyChainCostsMember_019b45dd-9d51-76f9-a7d7-9386b0de758f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TechnicalServicesMember_019b45dd-9d51-7ee6-aa4d-07520278dc85" xlink:href="tlx-20251231.xsd#tlx_TechnicalServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:to="loc_tlx_TechnicalServicesMember_019b45dd-9d51-7ee6-aa4d-07520278dc85" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GlobalManufacturingCostsMember_019b45dd-9d51-7035-bd30-7014fc189585" xlink:href="tlx-20251231.xsd#tlx_GlobalManufacturingCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019bfca1-2e8f-7649-8ce0-ccf0cf6e10ba" xlink:to="loc_tlx_GlobalManufacturingCostsMember_019b45dd-9d51-7035-bd30-7014fc189585" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingAndDistributionCosts_019b45dd-9d51-7406-b54e-7a556e617d84" xlink:href="tlx-20251231.xsd#tlx_ManufacturingAndDistributionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019b45dd-9d51-7322-9482-8f0beadf6a23" xlink:to="loc_tlx_ManufacturingAndDistributionCosts_019b45dd-9d51-7406-b54e-7a556e617d84" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ManufacturinganddistributioncostsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ManufacturinganddistributioncostsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ManufacturinganddistributioncostsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543b-0964-7523-b9ce-5747f7ffde6b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be599-5211-7f73-bc0e-0ebac4423790" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543b-0964-7523-b9ce-5747f7ffde6b" xlink:to="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be599-5211-7f73-bc0e-0ebac4423790" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019c543a-5d35-7f6b-b97d-6acb569c3433" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be599-5211-7f73-bc0e-0ebac4423790" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019c543a-5d35-7f6b-b97d-6acb569c3433" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543a-5d35-7f6b-b97d-6acb569c3433_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543a-5d35-7f6b-b97d-6acb569c3433" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543a-5d35-7f6b-b97d-6acb569c3433_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543a-5d35-776d-9d61-214d52d13d83" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543a-5d35-7f6b-b97d-6acb569c3433" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543a-5d35-776d-9d61-214d52d13d83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c543a-7af9-7b4b-8373-652e9f0f74c8" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019c543a-5d35-776d-9d61-214d52d13d83" xlink:to="loc_tlx_RLSMember_019c543a-7af9-7b4b-8373-652e9f0f74c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543b-0964-77da-aac3-2f4cd1697003" xlink:href="tlx-20251231.xsd#tlx_ContributionToCostsSinceAcquisitionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543b-0964-7523-b9ce-5747f7ffde6b" xlink:to="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543b-0964-77da-aac3-2f4cd1697003" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/GeneralandadministrationcostsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#GeneralandadministrationcostsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/GeneralandadministrationcostsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543c-99d0-7b52-a7da-b8fa2651ea93" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019c543c-99d0-73e4-9124-fa37618691d3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543c-99d0-7b52-a7da-b8fa2651ea93" xlink:to="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019c543c-99d0-73e4-9124-fa37618691d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019c543c-99d0-7700-bd58-0994cfb7226e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019c543c-99d0-73e4-9124-fa37618691d3" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019c543c-99d0-7700-bd58-0994cfb7226e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543c-99d0-7700-bd58-0994cfb7226e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543c-99d0-7700-bd58-0994cfb7226e" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543c-99d0-7700-bd58-0994cfb7226e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543c-99d0-7126-9c2e-20effcf1ec88" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543c-99d0-7700-bd58-0994cfb7226e" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543c-99d0-7126-9c2e-20effcf1ec88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c543c-99d0-7649-b0ec-8e7e0b1c5fcb" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019c543c-99d0-7126-9c2e-20effcf1ec88" xlink:to="loc_tlx_RLSMember_019c543c-99d0-7649-b0ec-8e7e0b1c5fcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543c-99d0-7d86-b005-4c9c3786085f" xlink:href="tlx-20251231.xsd#tlx_ContributionToCostsSinceAcquisitionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019c543c-99d0-7b52-a7da-b8fa2651ea93" xlink:to="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543c-99d0-7d86-b005-4c9c3786085f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EmploymentcostsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EmploymentcostsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EmploymentcostsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019be8f0-362b-7e28-9593-492527eaacfb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be8ef-f40c-7f95-992a-7a3ff661ae66" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019be8f0-362b-7e28-9593-492527eaacfb" xlink:to="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be8ef-f40c-7f95-992a-7a3ff661ae66" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionAxis_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AttributionOfExpensesByNatureToTheirFunctionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be8ef-f40c-7f95-992a-7a3ff661ae66" xlink:to="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionAxis_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionAxis_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe" xlink:to="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain_019be8f0-6b3b-7e44-8ef0-8eddc29c25b4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionAxis_019be8f0-6b3b-79b9-a6d6-cad41f99f1fe" xlink:to="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain_019be8f0-6b3b-7e44-8ef0-8eddc29c25b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CostOfSalesMember_019be8f0-6b3b-7444-9913-3d6494bd9c2c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AttributionOfExpensesByNatureToTheirFunctionDomain_019be8f0-6b3b-7e44-8ef0-8eddc29c25b4" xlink:to="loc_ifrs-full_CostOfSalesMember_019be8f0-6b3b-7444-9913-3d6494bd9c2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019c543d-9f06-7160-859c-6c21094b08b9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionTable_019be8ef-f40c-7f95-992a-7a3ff661ae66" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019c543d-9f06-7160-859c-6c21094b08b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543d-9f06-7160-859c-6c21094b08b9_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543d-9f06-7160-859c-6c21094b08b9" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543d-9f06-7160-859c-6c21094b08b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c543d-9f06-7b66-8148-e6414b4163bd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c543d-9f06-7160-859c-6c21094b08b9" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c543d-9f06-7b66-8148-e6414b4163bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c543d-9f06-774d-9776-c8524d9b673d" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019c543d-9f06-7b66-8148-e6414b4163bd" xlink:to="loc_tlx_RLSMember_019c543d-9f06-774d-9776-c8524d9b673d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WagesAndSalaries_019be59b-1d52-78d7-b8f3-e2337223f6f1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WagesAndSalaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019be8f0-362b-7e28-9593-492527eaacfb" xlink:to="loc_ifrs-full_WagesAndSalaries_019be59b-1d52-78d7-b8f3-e2337223f6f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543d-9f06-75be-a97a-ea659a8d6565" xlink:href="tlx-20251231.xsd#tlx_ContributionToCostsSinceAcquisitionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAttributionOfExpensesByNatureToTheirFunctionLineItems_019be8f0-362b-7e28-9593-492527eaacfb" xlink:to="loc_tlx_ContributionToCostsSinceAcquisitionTerm_019c543d-9f06-75be-a97a-ea659a8d6565" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EarningspershareDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EarningspershareDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EarningspershareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareTable_019b3a59-2520-7bab-ae88-1f3cff32fac2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:to="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareTable_019b3a59-2520-7bab-ae88-1f3cff32fac2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfAntidilutiveInstrumentsAxis_019b3a59-77b9-7b24-a9d9-d19643f3ec50" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfAntidilutiveInstrumentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareTable_019b3a59-2520-7bab-ae88-1f3cff32fac2" xlink:to="loc_ifrs-full_TypesOfAntidilutiveInstrumentsAxis_019b3a59-77b9-7b24-a9d9-d19643f3ec50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfAntidilutiveInstrumentsDomain_019b3a59-77b9-7b24-a9d9-d19643f3ec50_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfAntidilutiveInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfAntidilutiveInstrumentsAxis_019b3a59-77b9-7b24-a9d9-d19643f3ec50" xlink:to="loc_ifrs-full_TypesOfAntidilutiveInstrumentsDomain_019b3a59-77b9-7b24-a9d9-d19643f3ec50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfAntidilutiveInstrumentsDomain_019b3a59-77b9-7334-b5ff-d20c67e337f6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfAntidilutiveInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfAntidilutiveInstrumentsAxis_019b3a59-77b9-7b24-a9d9-d19643f3ec50" xlink:to="loc_ifrs-full_TypesOfAntidilutiveInstrumentsDomain_019b3a59-77b9-7334-b5ff-d20c67e337f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ShareOptionsMember_019b3a59-8bc4-7f3d-947f-f719bedd4dea" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShareOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfAntidilutiveInstrumentsDomain_019b3a59-77b9-7334-b5ff-d20c67e337f6" xlink:to="loc_ifrs-full_ShareOptionsMember_019b3a59-8bc4-7f3d-947f-f719bedd4dea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BasicEarningsPerShareAbstract_019b0124-04a3-76cd-93ed-53f973de6a5d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BasicEarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:to="loc_ifrs-full_BasicEarningsPerShareAbstract_019b0124-04a3-76cd-93ed-53f973de6a5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BasicEarningsLossPerShareFromContinuingOperations_019b0124-04a3-729e-88ab-d47a9210fdf7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BasicEarningsLossPerShareFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BasicEarningsPerShareAbstract_019b0124-04a3-76cd-93ed-53f973de6a5d" xlink:to="loc_ifrs-full_BasicEarningsLossPerShareFromContinuingOperations_019b0124-04a3-729e-88ab-d47a9210fdf7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BasicEarningsLossPerShare_019b0124-04a3-7af2-b737-cb5d9336b8ee" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BasicEarningsLossPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BasicEarningsPerShareAbstract_019b0124-04a3-76cd-93ed-53f973de6a5d" xlink:to="loc_ifrs-full_BasicEarningsLossPerShare_019b0124-04a3-7af2-b737-cb5d9336b8ee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DilutedEarningsPerShareAbstract_019b0124-04a3-70b7-9af6-415de12dd8fb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DilutedEarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:to="loc_ifrs-full_DilutedEarningsPerShareAbstract_019b0124-04a3-70b7-9af6-415de12dd8fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DilutedEarningsLossPerShareFromContinuingOperations_019b0124-04a3-7756-9ffb-34f142e34fa6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DilutedEarningsLossPerShareFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DilutedEarningsPerShareAbstract_019b0124-04a3-70b7-9af6-415de12dd8fb" xlink:to="loc_ifrs-full_DilutedEarningsLossPerShareFromContinuingOperations_019b0124-04a3-7756-9ffb-34f142e34fa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DilutedEarningsLossPerShare_019b0124-04a3-7579-bd1b-35c3995f05c5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DilutedEarningsLossPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DilutedEarningsPerShareAbstract_019b0124-04a3-70b7-9af6-415de12dd8fb" xlink:to="loc_ifrs-full_DilutedEarningsLossPerShare_019b0124-04a3-7579-bd1b-35c3995f05c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageSharesAndAdjustedWeightedAverageSharesAbstract_019b0124-04a3-7ed9-ae49-151c96379359" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageSharesAndAdjustedWeightedAverageSharesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:to="loc_ifrs-full_WeightedAverageSharesAndAdjustedWeightedAverageSharesAbstract_019b0124-04a3-7ed9-ae49-151c96379359" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageShares_019b0124-04a3-7ee1-997f-d6b6cf16eea3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_WeightedAverageSharesAndAdjustedWeightedAverageSharesAbstract_019b0124-04a3-7ed9-ae49-151c96379359" xlink:to="loc_ifrs-full_WeightedAverageShares_019b0124-04a3-7ee1-997f-d6b6cf16eea3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdjustedWeightedAverageShares_019b0124-04a3-7dc0-a910-ed40da14af22" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustedWeightedAverageShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_WeightedAverageSharesAndAdjustedWeightedAverageSharesAbstract_019b0124-04a3-7ed9-ae49-151c96379359" xlink:to="loc_ifrs-full_AdjustedWeightedAverageShares_019b0124-04a3-7dc0-a910-ed40da14af22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfPotentialOrdinarySharesThatAreAntidilutiveInPeriodPresented_019b3a58-febe-781c-a83c-0edb69be0d04" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfPotentialOrdinarySharesThatAreAntidilutiveInPeriodPresented"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInstrumentsWithPotentialFutureDilutiveEffectNotIncludedInCalculationOfDilutedEarningsPerShareLineItems_019b3a59-5a12-748a-9ec0-7951141f5eff" xlink:to="loc_ifrs-full_NumberOfPotentialOrdinarySharesThatAreAntidilutiveInPeriodPresented_019b3a58-febe-781c-a83c-0edb69be0d04" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/TradeandotherreceivablesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#TradeandotherreceivablesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/TradeandotherreceivablesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems_019be8fa-05a8-7744-9c9a-9dbe3b3087b6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable_019be8f9-d158-7055-85ff-6851b5fea966" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems_019be8fa-05a8-7744-9c9a-9dbe3b3087b6" xlink:to="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable_019be8f9-d158-7055-85ff-6851b5fea966" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be8fa-d6fb-7003-9025-8e4cecc67727" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable_019be8f9-d158-7055-85ff-6851b5fea966" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be8fa-d6fb-7003-9025-8e4cecc67727" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be8fa-d6fb-7003-9025-8e4cecc67727_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be8fa-d6fb-7003-9025-8e4cecc67727" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be8fa-d6fb-7003-9025-8e4cecc67727_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be8fa-d6fb-77c6-b4e8-27327b062687" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be8fa-d6fb-7003-9025-8e4cecc67727" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be8fa-d6fb-77c6-b4e8-27327b062687" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeReceivablesMember_019be8fb-382d-75e1-9507-e219064cdd02" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be8fa-d6fb-77c6-b4e8-27327b062687" xlink:to="loc_ifrs-full_TradeReceivablesMember_019be8fb-382d-75e1-9507-e219064cdd02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be8fc-7193-748d-9b33-f375d513df3e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable_019be8f9-d158-7055-85ff-6851b5fea966" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be8fc-7193-748d-9b33-f375d513df3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-748d-9b33-f375d513df3e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be8fc-7193-748d-9b33-f375d513df3e" xlink:to="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-748d-9b33-f375d513df3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-7cf7-a7d7-ffecddb197c7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be8fc-7193-748d-9b33-f375d513df3e" xlink:to="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-7cf7-a7d7-ffecddb197c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossCarryingAmountMember_019be8fc-afae-7020-b634-dc56a198881f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossCarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-7cf7-a7d7-ffecddb197c7" xlink:to="loc_ifrs-full_GrossCarryingAmountMember_019be8fc-afae-7020-b634-dc56a198881f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedImpairmentMember_019be8fc-e421-7e88-a661-ecd001791e5f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedImpairmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be8fc-7193-7cf7-a7d7-ffecddb197c7" xlink:to="loc_ifrs-full_AccumulatedImpairmentMember_019be8fc-e421-7e88-a661-ecd001791e5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialAssets_019be8fa-d6fb-7844-a13a-f1cd02a84bd6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems_019be8fa-05a8-7744-9c9a-9dbe3b3087b6" xlink:to="loc_ifrs-full_FinancialAssets_019be8fa-d6fb-7844-a13a-f1cd02a84bd6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialassetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialassetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialassetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems_019b0124-04a3-7972-a451-cd223e3b194c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesTable_019b0124-04a3-7908-8b72-fc7283cbac23" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems_019b0124-04a3-7972-a451-cd223e3b194c" xlink:to="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesTable_019b0124-04a3-7908-8b72-fc7283cbac23" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInAssociatesAxis_019b0124-04a3-79e2-967a-5cf39d9f4cbe" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInAssociatesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesTable_019b0124-04a3-7908-8b72-fc7283cbac23" xlink:to="loc_ifrs-full_SignificantInvestmentsInAssociatesAxis_019b0124-04a3-79e2-967a-5cf39d9f4cbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-79e2-967a-5cf39d9f4cbe_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInAssociatesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SignificantInvestmentsInAssociatesAxis_019b0124-04a3-79e2-967a-5cf39d9f4cbe" xlink:to="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-79e2-967a-5cf39d9f4cbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-74d3-a257-b2142a721bb7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInAssociatesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SignificantInvestmentsInAssociatesAxis_019b0124-04a3-79e2-967a-5cf39d9f4cbe" xlink:to="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-74d3-a257-b2142a721bb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MaunaKeaTechnologiesMember_019b0124-04a3-7e1b-8ebe-4df291b7643c" xlink:href="tlx-20251231.xsd#tlx_MaunaKeaTechnologiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-74d3-a257-b2142a721bb7" xlink:to="loc_tlx_MaunaKeaTechnologiesMember_019b0124-04a3-7e1b-8ebe-4df291b7643c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_AtoncoSASMember_019b0124-04a3-7ca5-853d-9f132bcbb9fe" xlink:href="tlx-20251231.xsd#tlx_AtoncoSASMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-74d3-a257-b2142a721bb7" xlink:to="loc_tlx_AtoncoSASMember_019b0124-04a3-7ca5-853d-9f132bcbb9fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IRMASurgicalMember_019b9d63-ec2a-73e0-b58d-045d98dbc10d" xlink:href="tlx-20251231.xsd#tlx_IRMASurgicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInAssociatesDomain_019b0124-04a3-74d3-a257-b2142a721bb7" xlink:to="loc_tlx_IRMASurgicalMember_019b9d63-ec2a-73e0-b58d-045d98dbc10d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfFinancialAssetsAbstract_019b0124-04a3-7c66-9737-ddcf3bee3fd8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfFinancialAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems_019b0124-04a3-7972-a451-cd223e3b194c" xlink:to="loc_ifrs-full_DisclosureOfFinancialAssetsAbstract_019b0124-04a3-7c66-9737-ddcf3bee3fd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentFinancialAssets_019b0124-04a3-70dd-82ed-e0a639fda691" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfFinancialAssetsAbstract_019b0124-04a3-7c66-9737-ddcf3bee3fd8" xlink:to="loc_ifrs-full_NoncurrentFinancialAssets_019b0124-04a3-70dd-82ed-e0a639fda691" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentRestrictedCashAndCashEquivalents_019b0124-04a3-72f4-829f-6c09b4b8763d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentRestrictedCashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfFinancialAssetsAbstract_019b0124-04a3-7c66-9737-ddcf3bee3fd8" xlink:to="loc_ifrs-full_NoncurrentRestrictedCashAndCashEquivalents_019b0124-04a3-72f4-829f-6c09b4b8763d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherFinancialAssetsMaximumDepositTerm_019be90b-e411-7b92-9cab-8ad9efd693b8" xlink:href="tlx-20251231.xsd#tlx_OtherFinancialAssetsMaximumDepositTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems_019b0124-04a3-7972-a451-cd223e3b194c" xlink:to="loc_tlx_OtherFinancialAssetsMaximumDepositTerm_019be90b-e411-7b92-9cab-8ad9efd693b8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofDeferredTaxAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofDeferredTaxAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofDeferredTaxAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b3ac0-a7b4-76c1-aaa2-5c5060ec7606" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b3ac0-a7b4-79a8-95fe-863002925a61" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b3ac0-a7b4-76c1-aaa2-5c5060ec7606" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b3ac0-a7b4-79a8-95fe-863002925a61" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b3ac0-a7b4-7587-9ef6-5235fa5ca674" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b3ac0-a7b4-79a8-95fe-863002925a61" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b3ac0-a7b4-7587-9ef6-5235fa5ca674" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7587-9ef6-5235fa5ca674_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b3ac0-a7b4-7587-9ef6-5235fa5ca674" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7587-9ef6-5235fa5ca674_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b3ac0-a7b4-7587-9ef6-5235fa5ca674" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnusedTaxLossesMember_019b3ac0-a7b4-7d2e-8f30-84ed638ca418" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnusedTaxLossesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_ifrs-full_UnusedTaxLossesMember_019b3ac0-a7b4-7d2e-8f30-84ed638ca418" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntangibleAssetsMember_019b3ac0-a7b4-712a-a619-a16ebfa3e079" xlink:href="tlx-20251231.xsd#tlx_IntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_tlx_IntangibleAssetsMember_019b3ac0-a7b4-712a-a619-a16ebfa3e079" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EmployeeBenefitObligationsMember_019b3ac0-a7b4-74cc-b599-dc035b9626a4" xlink:href="tlx-20251231.xsd#tlx_EmployeeBenefitObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_tlx_EmployeeBenefitObligationsMember_019b3ac0-a7b4-74cc-b599-dc035b9626a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseLiabilitiesMember_019b3ac0-a7b4-7cfe-ad19-6071f3d461ac" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_ifrs-full_LeaseLiabilitiesMember_019b3ac0-a7b4-7cfe-ad19-6071f3d461ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryNetMember_019b3ac0-a7b4-7666-a41f-4ca61973c63d" xlink:href="tlx-20251231.xsd#tlx_InventoryNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_tlx_InventoryNetMember_019b3ac0-a7b4-7666-a41f-4ca61973c63d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherTemporaryDifferencesMember_019b3ac0-a7b4-7bec-9d3c-4a783c225ef7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherTemporaryDifferencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b3ac0-a7b4-7034-b2ab-d75f199dba4a" xlink:to="loc_ifrs-full_OtherTemporaryDifferencesMember_019b3ac0-a7b4-7bec-9d3c-4a783c225ef7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetsAbstract_019b3ac3-8571-7ddb-9f75-ad9297402526" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b3ac0-a7b4-76c1-aaa2-5c5060ec7606" xlink:to="loc_tlx_DeferredTaxAssetsAbstract_019b3ac3-8571-7ddb-9f75-ad9297402526" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetGross_019b3ac0-a7b4-7ada-9041-e22de532b420" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DeferredTaxAssetsAbstract_019b3ac3-8571-7ddb-9f75-ad9297402526" xlink:to="loc_tlx_DeferredTaxAssetGross_019b3ac0-a7b4-7ada-9041-e22de532b420" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilitiesPursuantToSetOffProvisions_019b3ac0-a7b4-71fd-99f7-8194dde3f966" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilitiesPursuantToSetOffProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DeferredTaxAssetsAbstract_019b3ac3-8571-7ddb-9f75-ad9297402526" xlink:to="loc_tlx_DeferredTaxLiabilitiesPursuantToSetOffProvisions_019b3ac0-a7b4-71fd-99f7-8194dde3f966" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxAssets_019b3ac0-a7b4-716d-a520-169f77886bb4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DeferredTaxAssetsAbstract_019b3ac3-8571-7ddb-9f75-ad9297402526" xlink:to="loc_ifrs-full_DeferredTaxAssets_019b3ac0-a7b4-716d-a520-169f77886bb4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7c48-b5d6-8c3be17ca59e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-772a-aca2-02559a8e5418" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7c48-b5d6-8c3be17ca59e" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-772a-aca2-02559a8e5418" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7deb-b4be-4905468d9ae2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-772a-aca2-02559a8e5418" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7deb-b4be-4905468d9ae2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-7deb-b4be-4905468d9ae2_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7deb-b4be-4905468d9ae2" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-7deb-b4be-4905468d9ae2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7deb-b4be-4905468d9ae2" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnusedTaxLossesMember_019b0124-04a3-7523-bfdc-8898910645a0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnusedTaxLossesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_ifrs-full_UnusedTaxLossesMember_019b0124-04a3-7523-bfdc-8898910645a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntangibleAssetsMember_019b0124-04a3-7ac3-be4a-00630e3787da" xlink:href="tlx-20251231.xsd#tlx_IntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_tlx_IntangibleAssetsMember_019b0124-04a3-7ac3-be4a-00630e3787da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EmployeeBenefitObligationsMember_019b0124-04a3-719f-b1bf-c78eb21cc115" xlink:href="tlx-20251231.xsd#tlx_EmployeeBenefitObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_tlx_EmployeeBenefitObligationsMember_019b0124-04a3-719f-b1bf-c78eb21cc115" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-04a3-7f25-bed0-d8ecb12d0700" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-04a3-7f25-bed0-d8ecb12d0700" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryNetMember_019b0124-04a3-75e9-ba88-9b8b45e418f4" xlink:href="tlx-20251231.xsd#tlx_InventoryNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_tlx_InventoryNetMember_019b0124-04a3-75e9-ba88-9b8b45e418f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherTemporaryDifferencesMember_019b0124-04a3-7c42-8a1c-cf1a4441d816" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherTemporaryDifferencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-732c-830b-732a36fbb411" xlink:to="loc_ifrs-full_OtherTemporaryDifferencesMember_019b0124-04a3-7c42-8a1c-cf1a4441d816" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be90d-bc92-715f-9f41-a47c9dd9ede5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7c48-b5d6-8c3be17ca59e" xlink:to="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be90d-bc92-715f-9f41-a47c9dd9ede5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetGross_019b0124-04a3-7609-8c9d-836d59e40415" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be90d-bc92-715f-9f41-a47c9dd9ede5" xlink:to="loc_tlx_DeferredTaxAssetGross_019b0124-04a3-7609-8c9d-836d59e40415" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughBusinessCombinationsDeferredTaxLiabilityAsset_019c5524-88a4-7df5-8753-3a537a32c8b1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughBusinessCombinationsDeferredTaxLiabilityAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be90d-bc92-715f-9f41-a47c9dd9ede5" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughBusinessCombinationsDeferredTaxLiabilityAsset_019c5524-88a4-7df5-8753-3a537a32c8b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxExpenseIncomeRecognisedInProfitOrLoss_019b0124-04a3-79be-95f9-a6af039e5040" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxExpenseIncomeRecognisedInProfitOrLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be90d-bc92-715f-9f41-a47c9dd9ede5" xlink:to="loc_ifrs-full_DeferredTaxExpenseIncomeRecognisedInProfitOrLoss_019b0124-04a3-79be-95f9-a6af039e5040" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetGross_019b0124-04a3-7f1c-8d55-a29599c163d0" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetGross"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofDeferredTaxLiabilitiesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofDeferredTaxLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofDeferredTaxLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be90f-11db-7b88-a368-4fe2393ef00f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be90f-11db-7450-add4-6279912bf133" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be90f-11db-7b88-a368-4fe2393ef00f" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be90f-11db-7450-add4-6279912bf133" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be90f-11db-7abf-b983-862821a9ecb4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be90f-11db-7450-add4-6279912bf133" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be90f-11db-7abf-b983-862821a9ecb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-7abf-b983-862821a9ecb4_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be90f-11db-7abf-b983-862821a9ecb4" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-7abf-b983-862821a9ecb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-70c1-a212-c1818fb25896" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be90f-11db-7abf-b983-862821a9ecb4" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-70c1-a212-c1818fb25896" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntangibleAssetsMember_019be90f-11db-72c8-9c6b-084fdb90cae5" xlink:href="tlx-20251231.xsd#tlx_IntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-70c1-a212-c1818fb25896" xlink:to="loc_tlx_IntangibleAssetsMember_019be90f-11db-72c8-9c6b-084fdb90cae5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RightofuseAssetsMember_019be90f-11db-7f40-b48c-713c670bd27a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RightofuseAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-70c1-a212-c1818fb25896" xlink:to="loc_ifrs-full_RightofuseAssetsMember_019be90f-11db-7f40-b48c-713c670bd27a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnrealisedForeignExchangeGainsLossesMember_019be90f-11db-776a-8971-be84cf50f6ce" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnrealisedForeignExchangeGainsLossesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be90f-11db-70c1-a212-c1818fb25896" xlink:to="loc_ifrs-full_UnrealisedForeignExchangeGainsLossesMember_019be90f-11db-776a-8971-be84cf50f6ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilitiesGross_019be90f-11db-7702-a64a-bc19bc436b0f" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilitiesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be90f-11db-7b88-a368-4fe2393ef00f" xlink:to="loc_tlx_DeferredTaxLiabilitiesGross_019be90f-11db-7702-a64a-bc19bc436b0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetsPursuantToSetOffProvisions_019be90f-11db-79ca-acce-0e9e9c6e67ff" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetsPursuantToSetOffProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be90f-11db-7b88-a368-4fe2393ef00f" xlink:to="loc_tlx_DeferredTaxAssetsPursuantToSetOffProvisions_019be90f-11db-79ca-acce-0e9e9c6e67ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxLiabilities_019be90f-11db-7fb8-a180-e6f46fa69a0c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be90f-11db-7b88-a368-4fe2393ef00f" xlink:to="loc_ifrs-full_DeferredTaxLiabilities_019be90f-11db-7fb8-a180-e6f46fa69a0c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxLiabilitiesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofMovementsinDeferredTaxLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be910-e1c9-782b-b67a-9ce8a4070bc7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be910-e1c9-7228-99ac-20ac873c4d43" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be910-e1c9-782b-b67a-9ce8a4070bc7" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be910-e1c9-7228-99ac-20ac873c4d43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be910-e1c9-7873-b436-cb6cc0fc7d2b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019be910-e1c9-7228-99ac-20ac873c4d43" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be910-e1c9-7873-b436-cb6cc0fc7d2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7873-b436-cb6cc0fc7d2b_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be910-e1c9-7873-b436-cb6cc0fc7d2b" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7873-b436-cb6cc0fc7d2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7623-aac3-4f029ef47648" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019be910-e1c9-7873-b436-cb6cc0fc7d2b" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7623-aac3-4f029ef47648" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntangibleAssetsMember_019be910-e1c9-7e00-9901-45312acb0644" xlink:href="tlx-20251231.xsd#tlx_IntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7623-aac3-4f029ef47648" xlink:to="loc_tlx_IntangibleAssetsMember_019be910-e1c9-7e00-9901-45312acb0644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RightofuseAssetsMember_019be910-e1c9-753a-9fd2-3482aa0730d4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RightofuseAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7623-aac3-4f029ef47648" xlink:to="loc_ifrs-full_RightofuseAssetsMember_019be910-e1c9-753a-9fd2-3482aa0730d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnrealisedForeignExchangeGainsLossesMember_019be910-e1c9-7fda-955c-c7d8640acb21" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnrealisedForeignExchangeGainsLossesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019be910-e1c9-7623-aac3-4f029ef47648" xlink:to="loc_ifrs-full_UnrealisedForeignExchangeGainsLossesMember_019be910-e1c9-7fda-955c-c7d8640acb21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be912-004a-71df-a969-5d89956d1e32" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019be910-e1c9-782b-b67a-9ce8a4070bc7" xlink:to="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be912-004a-71df-a969-5d89956d1e32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilitiesGross_019be910-e1c9-7a05-9f60-2eed3ec75fdb" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilitiesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be912-004a-71df-a969-5d89956d1e32" xlink:to="loc_tlx_DeferredTaxLiabilitiesGross_019be910-e1c9-7a05-9f60-2eed3ec75fdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilityOnAcquisition_019bfcc8-2a13-7905-b163-d9ec0bdd6391" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilityOnAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be912-004a-71df-a969-5d89956d1e32" xlink:to="loc_tlx_DeferredTaxLiabilityOnAcquisition_019bfcc8-2a13-7905-b163-d9ec0bdd6391" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilityDeferredTaxExpenseIncomeRecognizedInProfitOrLoss_019be910-e1c9-7c05-beb8-4dde1b44720c" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilityDeferredTaxExpenseIncomeRecognizedInProfitOrLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract_019be912-004a-71df-a969-5d89956d1e32" xlink:to="loc_tlx_DeferredTaxLiabilityDeferredTaxExpenseIncomeRecognizedInProfitOrLoss_019be910-e1c9-7c05-beb8-4dde1b44720c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilitiesGross_019bfcb7-2cf5-7d9e-96cb-3f666d16052b" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilitiesGross"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofUnrecognizedDeferredTaxAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofUnrecognizedDeferredTaxAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofUnrecognizedDeferredTaxAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7d0b-857e-25d9fde65aef" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7ed9-a899-9074966ea103" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7d0b-857e-25d9fde65aef" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7ed9-a899-9074966ea103" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7f77-80da-6346b3d2aab6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7ed9-a899-9074966ea103" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7f77-80da-6346b3d2aab6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-7f77-80da-6346b3d2aab6_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7f77-80da-6346b3d2aab6" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-7f77-80da-6346b3d2aab6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-76d1-bfd9-0579ff330b88" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis_019b0124-04a3-7f77-80da-6346b3d2aab6" xlink:to="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-76d1-bfd9-0579ff330b88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TemporaryDifferenceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsDomain_019b0124-04a3-76d1-bfd9-0579ff330b88" xlink:to="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TaxLossesAndTaxCreditsMember_019b0124-04a3-721e-b328-6dc1f34362f1" xlink:href="tlx-20251231.xsd#tlx_TaxLossesAndTaxCreditsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_TaxLossesAndTaxCreditsMember_019b0124-04a3-721e-b328-6dc1f34362f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ProvisionsMember_019b0124-04a3-778f-9594-0c0aa82f5b22" xlink:href="tlx-20251231.xsd#tlx_ProvisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_ProvisionsMember_019b0124-04a3-778f-9594-0c0aa82f5b22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EmployeeBenefitObligationsMember_019b0124-04a3-79b0-8617-f4911f9213fe" xlink:href="tlx-20251231.xsd#tlx_EmployeeBenefitObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_EmployeeBenefitObligationsMember_019b0124-04a3-79b0-8617-f4911f9213fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IntangibleAssetsMember_019b0124-04a3-79b1-a57a-8b6f465e92e4" xlink:href="tlx-20251231.xsd#tlx_IntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_IntangibleAssetsMember_019b0124-04a3-79b1-a57a-8b6f465e92e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InventoryNettingMember_019c6d85-e85e-7ed7-976e-bb3e9168d22a" xlink:href="tlx-20251231.xsd#tlx_InventoryNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_InventoryNettingMember_019c6d85-e85e-7ed7-976e-bb3e9168d22a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-04a3-7cc3-a32e-ff69b4b8083e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-04a3-7cc3-a32e-ff69b4b8083e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ShareBasedPaymentsMember_019b0124-04a3-709e-aade-827d22cb52c8" xlink:href="tlx-20251231.xsd#tlx_ShareBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TemporaryDifferenceMember_019b0124-04a3-7e41-b392-ddf7441aa95f" xlink:to="loc_tlx_ShareBasedPaymentsMember_019b0124-04a3-709e-aade-827d22cb52c8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised_019b0124-04a3-79f7-aa82-41dde0aec283" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7d0b-857e-25d9fde65aef" xlink:to="loc_ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised_019b0124-04a3-79f7-aa82-41dde0aec283" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofUnrecognizedTaxLossesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeferredtaxassetsandliabilitiesScheduleofUnrecognizedTaxLossesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeferredtaxassetsandliabilitiesScheduleofUnrecognizedTaxLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7a4c-a976-64c65b5d83dd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7fd1-a0a5-6ae148f73415" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7a4c-a976-64c65b5d83dd" xlink:to="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7fd1-a0a5-6ae148f73415" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a3-76b7-a368-42f147222cfa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable_019b0124-04a3-7fd1-a0a5-6ae148f73415" xlink:to="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a3-76b7-a368-42f147222cfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-76b7-a368-42f147222cfa_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a3-76b7-a368-42f147222cfa" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-76b7-a368-42f147222cfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-7cb7-8adb-97ffecc97210" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019b0124-04a3-76b7-a368-42f147222cfa" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-7cb7-8adb-97ffecc97210" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_AU_019b0124-04a3-703c-b9d7-68d1af1d0b57" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_AU"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-7cb7-8adb-97ffecc97210" xlink:to="loc_country_AU_019b0124-04a3-703c-b9d7-68d1af1d0b57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ForeignCountriesMember_019b0124-04a3-74b9-8d1b-2338ab233741" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ForeignCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019b0124-04a3-7cb7-8adb-97ffecc97210" xlink:to="loc_ifrs-full_ForeignCountriesMember_019b0124-04a3-74b9-8d1b-2338ab233741" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UnusedTaxLossesAndCreditsForWhichNoDeferredTaxAssetIsRecognised_019b0124-04a3-7a75-8110-bdc6b0d17597" xlink:href="tlx-20251231.xsd#tlx_UnusedTaxLossesAndCreditsForWhichNoDeferredTaxAssetIsRecognised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7a4c-a976-64c65b5d83dd" xlink:to="loc_tlx_UnusedTaxLossesAndCreditsForWhichNoDeferredTaxAssetIsRecognised_019b0124-04a3-7a75-8110-bdc6b0d17597" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UnusedTaxLossesAndCreditsForWhichDeferredTaxAssetIsRecognised_019c32e5-c383-77ac-8cdd-7714afbe853f" xlink:href="tlx-20251231.xsd#tlx_UnusedTaxLossesAndCreditsForWhichDeferredTaxAssetIsRecognised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems_019b0124-04a3-7a4c-a976-64c65b5d83dd" xlink:to="loc_tlx_UnusedTaxLossesAndCreditsForWhichDeferredTaxAssetIsRecognised_019c32e5-c383-77ac-8cdd-7714afbe853f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/PropertyplantandequipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#PropertyplantandequipmentScheduleofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/PropertyplantandequipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a3-7177-831b-c6143cb5a378" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a3-7d72-b542-f86821c7954b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a3-7177-831b-c6143cb5a378" xlink:to="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a3-7d72-b542-f86821c7954b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a3-7ad8-aa5c-af5fe3e1a396" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a3-7d72-b542-f86821c7954b" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a3-7ad8-aa5c-af5fe3e1a396" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-7ad8-aa5c-af5fe3e1a396_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a3-7ad8-aa5c-af5fe3e1a396" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-7ad8-aa5c-af5fe3e1a396_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis_019b0124-04a3-7ad8-aa5c-af5fe3e1a396" xlink:to="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LandAndBuildingsMember_019b0124-04a3-71b9-918a-92b2450bafca" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LandAndBuildingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:to="loc_ifrs-full_LandAndBuildingsMember_019b0124-04a3-71b9-918a-92b2450bafca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PlantEquipmentAndVehiclesMember_019c1231-6848-7f8c-b3f8-44178b56d934" xlink:href="tlx-20251231.xsd#tlx_PlantEquipmentAndVehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:to="loc_tlx_PlantEquipmentAndVehiclesMember_019c1231-6848-7f8c-b3f8-44178b56d934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FixturesAndFittingsMember_019b0124-04a3-79ee-a0b6-a4c089658b1a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FixturesAndFittingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:to="loc_ifrs-full_FixturesAndFittingsMember_019b0124-04a3-79ee-a0b6-a4c089658b1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseholdImprovementsMember_019b0124-04a3-7e69-873b-d2f24291c8da" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:to="loc_ifrs-full_LeaseholdImprovementsMember_019b0124-04a3-7e69-873b-d2f24291c8da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ConstructionInProgressMember_019bfccd-f746-7197-a13a-b93b88cc8730" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfPropertyPlantAndEquipmentDomain_019b0124-04a3-72b9-a398-b9bfba250fa4" xlink:to="loc_ifrs-full_ConstructionInProgressMember_019bfccd-f746-7197-a13a-b93b88cc8730" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be91c-0a38-70f1-af4e-e3bead3cd708" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable_019b0124-04a3-7d72-b542-f86821c7954b" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be91c-0a38-70f1-af4e-e3bead3cd708" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-70f1-af4e-e3bead3cd708_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be91c-0a38-70f1-af4e-e3bead3cd708" xlink:to="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-70f1-af4e-e3bead3cd708_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-7ad8-8def-5e716c8c62d2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be91c-0a38-70f1-af4e-e3bead3cd708" xlink:to="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-7ad8-8def-5e716c8c62d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossCarryingAmountMember_019be91f-01e0-772d-bb3d-4f59236e933c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossCarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-7ad8-8def-5e716c8c62d2" xlink:to="loc_ifrs-full_GrossCarryingAmountMember_019be91f-01e0-772d-bb3d-4f59236e933c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019be91e-bba3-75c1-bf61-d9387c29962d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be91c-0a38-7ad8-8def-5e716c8c62d2" xlink:to="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019be91e-bba3-75c1-bf61-d9387c29962d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems_019b0124-04a3-7177-831b-c6143cb5a378" xlink:to="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipment_019b0124-04a3-7a34-a5a6-0e5d9dfa81d4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_PropertyPlantAndEquipment_019b0124-04a3-7a34-a5a6-0e5d9dfa81d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment_019b0124-04a3-7e2c-aada-b11cfd6b82b4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment_019b0124-04a3-7e2c-aada-b11cfd6b82b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment_019b0124-04a3-71a6-872a-cbb5987993b6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment_019b0124-04a3-71a6-872a-cbb5987993b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment_019b0124-04a3-753f-b88a-3dc7caf4a83c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment_019b0124-04a3-753f-b88a-3dc7caf4a83c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseFromChangeInProvisionsPropertyPlantAndEquipment_019b0124-04a3-78c8-9d90-fe1bec92d25e" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseFromChangeInProvisionsPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_tlx_IncreaseDecreaseFromChangeInProvisionsPropertyPlantAndEquipment_019b0124-04a3-78c8-9d90-fe1bec92d25e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DepreciationPropertyPlantAndEquipment_019b0124-04a3-7c77-87be-866718fb39fc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DepreciationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_DepreciationPropertyPlantAndEquipment_019b0124-04a3-7c77-87be-866718fb39fc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment_019b0124-04a3-7f9c-8634-4bdd2a14dbeb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInPropertyPlantAndEquipmentAbstract_019b0124-04a3-72c0-82bb-e1e2cbbad8d5" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment_019b0124-04a3-7f9c-8634-4bdd2a14dbeb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipment_019b0124-04a3-76b6-a215-920305ee83c7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RightofuseassetsScheduleofRightofUseAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RightofuseassetsScheduleofRightofUseAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RightofuseassetsScheduleofRightofUseAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-75db-b878-d3b64614214d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-7cd2-b397-10aae3a74b47" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-75db-b878-d3b64614214d" xlink:to="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-7cd2-b397-10aae3a74b47" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7237-ad73-a2ca33f81f77" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-7cd2-b397-10aae3a74b47" xlink:to="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7237-ad73-a2ca33f81f77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7237-ad73-a2ca33f81f77_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7237-ad73-a2ca33f81f77" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7237-ad73-a2ca33f81f77_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7fbb-b213-cbbb54e1ab2b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7237-ad73-a2ca33f81f77" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7fbb-b213-cbbb54e1ab2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LandAndBuildingsMember_019c5455-aa0b-718c-8617-fb6fb7cf3238" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LandAndBuildingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7fbb-b213-cbbb54e1ab2b" xlink:to="loc_ifrs-full_LandAndBuildingsMember_019c5455-aa0b-718c-8617-fb6fb7cf3238" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MotorVehiclesMember_019b0124-04a3-7173-b4b5-4ab7919ae385" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MotorVehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7fbb-b213-cbbb54e1ab2b" xlink:to="loc_ifrs-full_MotorVehiclesMember_019b0124-04a3-7173-b4b5-4ab7919ae385" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-7cd2-b397-10aae3a74b47" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012" xlink:to="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-756b-b5b8-6bfb22cde3cd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019bc01b-c9e4-7bf8-bbd2-b2dd9c145012" xlink:to="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-756b-b5b8-6bfb22cde3cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossCarryingAmountMember_019bc01b-c9e4-7304-9ad6-922c545acded" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossCarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-756b-b5b8-6bfb22cde3cd" xlink:to="loc_ifrs-full_GrossCarryingAmountMember_019bc01b-c9e4-7304-9ad6-922c545acded" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019bc01b-c9e4-7061-aaf1-e15b180c159d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019bc01b-c9e4-756b-b5b8-6bfb22cde3cd" xlink:to="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019bc01b-c9e4-7061-aaf1-e15b180c159d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-75db-b878-d3b64614214d" xlink:to="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RightofuseAssets_019b0124-04a3-7df6-921a-66858584bdfc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_ifrs-full_RightofuseAssets_019b0124-04a3-7df6-921a-66858584bdfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdditionsToRightofuseAssets_019b0124-04a3-7924-a633-7d30f5a76f28" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdditionsToRightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_ifrs-full_AdditionsToRightofuseAssets_019b0124-04a3-7924-a633-7d30f5a76f28" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsRightofuseAssets_019b0124-04a3-79a8-8a06-3c720e379715" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitionsThroughBusinessCombinationsRightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsRightofuseAssets_019b0124-04a3-79a8-8a06-3c720e379715" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ReclassificationsRightOfUseAsset_019b0124-04a3-7df1-ae15-981e084f183c" xlink:href="tlx-20251231.xsd#tlx_ReclassificationsRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_tlx_ReclassificationsRightOfUseAsset_019b0124-04a3-7df1-ae15-981e084f183c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DepreciationRightofuseAssets_019b0124-04a3-798d-95c7-2e9380a83fcd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DepreciationRightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_ifrs-full_DepreciationRightofuseAssets_019b0124-04a3-798d-95c7-2e9380a83fcd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesRightofuseAssets_019b0124-04a3-7cc8-9389-c2f4b3e851d7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesRightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInRightofuseAssetsAbstract_019be922-d5de-76f9-b288-7aa36629a8a0" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesRightofuseAssets_019b0124-04a3-7cc8-9389-c2f4b3e851d7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RightofuseAssets_019b0124-04a3-7150-9e5e-6a31accb4ff5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RightofuseAssets"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RightofuseassetsScheduleofDepreciationChargeonRightofUseAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RightofuseassetsScheduleofDepreciationChargeonRightofUseAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RightofuseassetsScheduleofDepreciationChargeonRightofUseAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-7a0b-ad9c-ea2221a45bee" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-70f6-a4a3-9e6cc74c1c04" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-7a0b-ad9c-ea2221a45bee" xlink:to="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-70f6-a4a3-9e6cc74c1c04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7426-8d0a-6890b59d3733" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-04a3-70f6-a4a3-9e6cc74c1c04" xlink:to="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7426-8d0a-6890b59d3733" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7426-8d0a-6890b59d3733_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7426-8d0a-6890b59d3733" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7426-8d0a-6890b59d3733_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7023-b3da-2e5bfc3d689d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-04a3-7426-8d0a-6890b59d3733" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7023-b3da-2e5bfc3d689d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LandAndBuildingsMember_019c5456-6bc7-72ec-9fce-6835e53f7158" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LandAndBuildingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7023-b3da-2e5bfc3d689d" xlink:to="loc_ifrs-full_LandAndBuildingsMember_019c5456-6bc7-72ec-9fce-6835e53f7158" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MotorVehiclesMember_019b0124-04a3-78c3-baad-55e669ce2c3e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MotorVehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-04a3-7023-b3da-2e5bfc3d689d" xlink:to="loc_ifrs-full_MotorVehiclesMember_019b0124-04a3-78c3-baad-55e669ce2c3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DepreciationRightofuseAssets_019b0124-04a3-7dbb-aaa7-225bd42d16db" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DepreciationRightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-04a3-7a0b-ad9c-ea2221a45bee" xlink:to="loc_ifrs-full_DepreciationRightofuseAssets_019b0124-04a3-7dbb-aaa7-225bd42d16db" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/IntangibleassetsScheduleofIntangibleAssetsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#IntangibleassetsScheduleofIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/IntangibleassetsScheduleofIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a3-7ba7-b0c3-2ee0b5ef8563" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a3-70bb-80e5-929b654605e5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a3-7ba7-b0c3-2ee0b5ef8563" xlink:to="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a3-70bb-80e5-929b654605e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a3-7a4e-9eaf-9009e1242027" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a3-70bb-80e5-929b654605e5" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a3-7a4e-9eaf-9009e1242027" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7a4e-9eaf-9009e1242027_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a3-7a4e-9eaf-9009e1242027" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7a4e-9eaf-9009e1242027_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019b0124-04a3-7a4e-9eaf-9009e1242027" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodwillMember_019b0124-04a3-7908-a041-95c0e8da1977" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_ifrs-full_GoodwillMember_019b0124-04a3-7908-a041-95c0e8da1977" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BrandNamesMember_019b0124-04a3-7ec3-82ae-29944dde58c6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BrandNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_ifrs-full_BrandNamesMember_019b0124-04a3-7ec3-82ae-29944dde58c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CustomerRelationshipsAndBrandsMember_019b0124-04a3-7ad4-9e7f-dc3536450455" xlink:href="tlx-20251231.xsd#tlx_CustomerRelationshipsAndBrandsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_tlx_CustomerRelationshipsAndBrandsMember_019b0124-04a3-7ad4-9e7f-dc3536450455" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComputerSoftwareMember_019b0124-04a3-71ed-a6e0-eb5551e877cc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComputerSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_ifrs-full_ComputerSoftwareMember_019b0124-04a3-71ed-a6e0-eb5551e877cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember_019b0124-04a3-7d2a-8755-143272a31898" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember_019b0124-04a3-7d2a-8755-143272a31898" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LicencesMember_019b0124-04a3-7d6e-99f9-eab1c8f63444" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LicencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019b0124-04a3-7f7c-988d-8bb66fa0f32c" xlink:to="loc_ifrs-full_LicencesMember_019b0124-04a3-7d6e-99f9-eab1c8f63444" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be92e-bf21-752c-9df9-9eca34e1c83c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019b0124-04a3-70bb-80e5-929b654605e5" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be92e-bf21-752c-9df9-9eca34e1c83c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-752c-9df9-9eca34e1c83c_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be92e-bf21-752c-9df9-9eca34e1c83c" xlink:to="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-752c-9df9-9eca34e1c83c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-7e6f-bb6f-01650adbebf3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be92e-bf21-752c-9df9-9eca34e1c83c" xlink:to="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-7e6f-bb6f-01650adbebf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossCarryingAmountMember_019be92e-f613-7ed7-b17f-04a962e3dc37" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossCarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-7e6f-bb6f-01650adbebf3" xlink:to="loc_ifrs-full_GrossCarryingAmountMember_019be92e-f613-7ed7-b17f-04a962e3dc37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019be92f-4595-7c2b-9f6a-703bfaf2e836" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be92e-bf21-7e6f-bb6f-01650adbebf3" xlink:to="loc_ifrs-full_AccumulatedDepreciationAndAmortisationMember_019be92f-4595-7c2b-9f6a-703bfaf2e836" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsLineItems_019b0124-04a3-7ba7-b0c3-2ee0b5ef8563" xlink:to="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IntangibleAssetsAndGoodwill_019b0124-04a3-737a-91fe-8b0bcc3869ab" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_IntangibleAssetsAndGoodwill_019b0124-04a3-737a-91fe-8b0bcc3869ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill_019bfcd9-10f9-798b-8c60-4fc5baaec2cf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill_019bfcd9-10f9-798b-8c60-4fc5baaec2cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill_019b0124-04a3-74e4-800f-b2ad0eaa4f98" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill_019b0124-04a3-74e4-800f-b2ad0eaa4f98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughMeasurementPeriodAdjustmentsIntangibleAssetsAndGoodwill_019c32d5-0700-7c50-8bc6-3dfbe14ed406" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughMeasurementPeriodAdjustmentsIntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_tlx_IncreaseDecreaseThroughMeasurementPeriodAdjustmentsIntangibleAssetsAndGoodwill_019c32d5-0700-7c50-8bc6-3dfbe14ed406" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughTransfersIntangibleAssetsAndGoodwill_019bfcda-642c-7d06-92f3-fbabffb319b7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughTransfersIntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughTransfersIntangibleAssetsAndGoodwill_019bfcda-642c-7d06-92f3-fbabffb319b7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AmortisationIntangibleAssetsOtherThanGoodwill_019b0124-04a3-74e7-9be5-05f9ea1124b3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AmortisationIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_AmortisationIntangibleAssetsOtherThanGoodwill_019b0124-04a3-74e7-9be5-05f9ea1124b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill_019bfdb4-9407-7984-bca0-51e8fd7d208b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill_019bfdb4-9407-7984-bca0-51e8fd7d208b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughChangesInProvisionsIntangibleAssetsAndGoodwill_019b0124-04a3-78f8-885e-1577946a9575" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughChangesInProvisionsIntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_tlx_IncreaseDecreaseThroughChangesInProvisionsIntangibleAssetsAndGoodwill_019b0124-04a3-78f8-885e-1577946a9575" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesIntangibleAssetsAndGoodwill_019bfcdc-5d50-7d4a-8bbe-d4f40fd85344" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesIntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInIntangibleAssetsOtherThanGoodwillAbstract_019b0124-04a3-7969-a72a-d084e6707a5b" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesIntangibleAssetsAndGoodwill_019bfcdc-5d50-7d4a-8bbe-d4f40fd85344" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IntangibleAssetsAndGoodwill_019b0124-04a3-7026-b621-d62c57825188" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/IntangibleassetsScheduleofAllocationofIntangibleAssetstoEachCashGeneratingUnitDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#IntangibleassetsScheduleofAllocationofIntangibleAssetstoEachCashGeneratingUnitDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/IntangibleassetsScheduleofAllocationofIntangibleAssetstoEachCashGeneratingUnitDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019b0124-04a3-7aed-ad4a-8e6b0742c30b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019b0124-04a3-737e-910e-1f8548004c7a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019b0124-04a3-7aed-ad4a-8e6b0742c30b" xlink:to="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019b0124-04a3-737e-910e-1f8548004c7a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsAxis_019be936-1259-7e0b-8039-1f3a7d0036f1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019b0124-04a3-737e-910e-1f8548004c7a" xlink:to="loc_ifrs-full_SegmentsAxis_019be936-1259-7e0b-8039-1f3a7d0036f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019be936-1259-7e0b-8039-1f3a7d0036f1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SegmentsAxis_019be936-1259-7e0b-8039-1f3a7d0036f1" xlink:to="loc_ifrs-full_SegmentsDomain_019be936-1259-7e0b-8039-1f3a7d0036f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SegmentsDomain_019be936-5c63-7e03-a285-1e94fb6294ac" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SegmentsAxis_019be936-1259-7e0b-8039-1f3a7d0036f1" xlink:to="loc_ifrs-full_SegmentsDomain_019be936-5c63-7e03-a285-1e94fb6294ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PrecisionMedicineMember_019be936-9579-7623-b8b9-3d085387c38c" xlink:href="tlx-20251231.xsd#tlx_PrecisionMedicineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019be936-5c63-7e03-a285-1e94fb6294ac" xlink:to="loc_tlx_PrecisionMedicineMember_019be936-9579-7623-b8b9-3d085387c38c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeuticsMember_019be936-db8c-7eec-8ca7-7074a56309e4" xlink:href="tlx-20251231.xsd#tlx_TherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019be936-5c63-7e03-a285-1e94fb6294ac" xlink:to="loc_tlx_TherapeuticsMember_019be936-db8c-7eec-8ca7-7074a56309e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingSolutionsMember_019be937-21ec-7f28-8a25-2cbc5f6822eb" xlink:href="tlx-20251231.xsd#tlx_ManufacturingSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SegmentsDomain_019be936-5c63-7e03-a285-1e94fb6294ac" xlink:to="loc_tlx_ManufacturingSolutionsMember_019be937-21ec-7f28-8a25-2cbc5f6822eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a3-7801-acd2-671589988fff" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019b0124-04a3-737e-910e-1f8548004c7a" xlink:to="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a3-7801-acd2-671589988fff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7801-acd2-671589988fff_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a3-7801-acd2-671589988fff" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7801-acd2-671589988fff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-04a3-7801-acd2-671589988fff" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX591CDxIlluccixMember_019b0124-04a3-742b-ba20-76459ba0d08e" xlink:href="tlx-20251231.xsd#tlx_TLX591CDxIlluccixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX591CDxIlluccixMember_019b0124-04a3-742b-ba20-76459ba0d08e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX66-CDxMember_019b0124-04a3-733b-b9a7-39dc509d31c9" xlink:href="tlx-20251231.xsd#tlx_TLX66-CDxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX66-CDxMember_019b0124-04a3-733b-b9a7-39dc509d31c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX300CDxMember_019b0124-04a3-7197-a58c-8b3a42f12e68" xlink:href="tlx-20251231.xsd#tlx_TLX300CDxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX300CDxMember_019b0124-04a3-7197-a58c-8b3a42f12e68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember_019c128a-1c23-7302-8bf9-fc3b4129fa02" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_ifrs-full_CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember_019c128a-1c23-7302-8bf9-fc3b4129fa02" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SENSEIMember_019b0124-04a3-7647-991f-c5fd5b2b48e1" xlink:href="tlx-20251231.xsd#tlx_SENSEIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_SENSEIMember_019b0124-04a3-7647-991f-c5fd5b2b48e1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DedicaidQDOSEMember_019b0124-04a3-7fdb-9163-58422472ad19" xlink:href="tlx-20251231.xsd#tlx_DedicaidQDOSEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_DedicaidQDOSEMember_019b0124-04a3-7fdb-9163-58422472ad19" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX101TxMember_019b0124-04a3-7c34-8b54-11435513968d" xlink:href="tlx-20251231.xsd#tlx_TLX101TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX101TxMember_019b0124-04a3-7c34-8b54-11435513968d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX090TxMember_019c6ee2-8e73-7135-a0b8-a977de71778c" xlink:href="tlx-20251231.xsd#tlx_TLX090TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX090TxMember_019c6ee2-8e73-7135-a0b8-a977de71778c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX591TxMember_019c127e-52c4-7039-aa04-01c371ed073c" xlink:href="tlx-20251231.xsd#tlx_TLX591TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX591TxMember_019c127e-52c4-7039-aa04-01c371ed073c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX66TxMember_019c1280-1f36-73af-bd17-e3c080ff3d93" xlink:href="tlx-20251231.xsd#tlx_TLX66TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX66TxMember_019c1280-1f36-73af-bd17-e3c080ff3d93" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX300TxMember_019b0124-04a3-70ed-9e16-c230f41e45c2" xlink:href="tlx-20251231.xsd#tlx_TLX300TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX300TxMember_019b0124-04a3-70ed-9e16-c230f41e45c2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX400TxMember_019c6ee3-21ec-739a-bda3-bac03955ba97" xlink:href="tlx-20251231.xsd#tlx_TLX400TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TLX400TxMember_019c6ee3-21ec-739a-bda3-bac03955ba97" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixTargetingTechnologyMember_019c1282-3903-7279-a1c7-f9aa4f80aa9d" xlink:href="tlx-20251231.xsd#tlx_TelixTargetingTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_TelixTargetingTechnologyMember_019c1282-3903-7279-a1c7-f9aa4f80aa9d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSMember_019b0124-04a3-78a9-9ba9-3424061ab102" xlink:href="tlx-20251231.xsd#tlx_ARTMSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_ARTMSMember_019b0124-04a3-78a9-9ba9-3424061ab102" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c1282-a5b0-7791-9974-d5bf5a9155b2" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_RLSMember_019c1282-a5b0-7791-9974-d5bf5a9155b2" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IsoTherapeuticsMember_019b0124-04a3-7551-b800-e4ce8536f212" xlink:href="tlx-20251231.xsd#tlx_IsoTherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_IsoTherapeuticsMember_019b0124-04a3-7551-b800-e4ce8536f212" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BrusselsSouthAndSacramentoMember_019b0124-04a3-7df9-8e23-f80d386646f3" xlink:href="tlx-20251231.xsd#tlx_BrusselsSouthAndSacramentoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-04a3-7565-9275-c1fd188f2dd4" xlink:to="loc_tlx_BrusselsSouthAndSacramentoMember_019b0124-04a3-7df9-8e23-f80d386646f3" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TypeOfIntangiblesAxis_019c54ef-153b-777c-8bfe-1a54977677ba" xlink:href="tlx-20251231.xsd#tlx_TypeOfIntangiblesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019b0124-04a3-737e-910e-1f8548004c7a" xlink:to="loc_tlx_TypeOfIntangiblesAxis_019c54ef-153b-777c-8bfe-1a54977677ba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-777c-8bfe-1a54977677ba_default" xlink:href="tlx-20251231.xsd#tlx_TypeOfIntangiblesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_TypeOfIntangiblesAxis_019c54ef-153b-777c-8bfe-1a54977677ba" xlink:to="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-777c-8bfe-1a54977677ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-74ae-985c-c72ed1887bc2" xlink:href="tlx-20251231.xsd#tlx_TypeOfIntangiblesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_TypeOfIntangiblesAxis_019c54ef-153b-777c-8bfe-1a54977677ba" xlink:to="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-74ae-985c-c72ed1887bc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IndefiniteUsefulLifeMember_019c54ef-a09f-7227-b6d9-3ed3c26eacbe" xlink:href="tlx-20251231.xsd#tlx_IndefiniteUsefulLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-74ae-985c-c72ed1887bc2" xlink:to="loc_tlx_IndefiniteUsefulLifeMember_019c54ef-a09f-7227-b6d9-3ed3c26eacbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DefiniteUsefulLifeMember_019c54ef-e0bc-7123-82b8-156f3e6fd531" xlink:href="tlx-20251231.xsd#tlx_DefiniteUsefulLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TypeOfIntangiblesDomain_019c54ef-153b-74ae-985c-c72ed1887bc2" xlink:to="loc_tlx_DefiniteUsefulLifeMember_019c54ef-e0bc-7123-82b8-156f3e6fd531" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAbstract_019b0124-04a3-76c8-b075-5dc55fb13c13" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019b0124-04a3-7aed-ad4a-8e6b0742c30b" xlink:to="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAbstract_019b0124-04a3-76c8-b075-5dc55fb13c13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IntangibleAssetsOtherThanGoodwill_019b0124-04a3-7b4a-bbe2-f4ee5d055714" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAbstract_019b0124-04a3-76c8-b075-5dc55fb13c13" xlink:to="loc_ifrs-full_IntangibleAssetsOtherThanGoodwill_019b0124-04a3-7b4a-bbe2-f4ee5d055714" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/IntangibleassetsGoodwillallocationperCGUDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#IntangibleassetsGoodwillallocationperCGUDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/IntangibleassetsGoodwillallocationperCGUDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c5518-b001-79f4-8874-9d5704ace735" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c5518-b001-7533-982c-c439df5ead69" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c5518-b001-79f4-8874-9d5704ace735" xlink:to="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c5518-b001-7533-982c-c439df5ead69" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis_019c5518-b001-7587-9d77-4cc945256ccd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c5518-b001-7533-982c-c439df5ead69" xlink:to="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis_019c5518-b001-7587-9d77-4cc945256ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7587-9d77-4cc945256ccd_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis_019c5518-b001-7587-9d77-4cc945256ccd" xlink:to="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7587-9d77-4cc945256ccd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis_019c5518-b001-7587-9d77-4cc945256ccd" xlink:to="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BrusselsSouthAndSacramentoMember_019c7297-3829-7a87-8939-3f0dfbe97ed0" xlink:href="tlx-20251231.xsd#tlx_BrusselsSouthAndSacramentoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_BrusselsSouthAndSacramentoMember_019c7297-3829-7a87-8939-3f0dfbe97ed0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c5518-b001-73fd-bb52-7be1dfc07b5a" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_RLSMember_019c5518-b001-73fd-bb52-7be1dfc07b5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IsoTherapeuticsMember_019c5518-b001-7d0b-bcbe-2d3121799d0e" xlink:href="tlx-20251231.xsd#tlx_IsoTherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_IsoTherapeuticsMember_019c5518-b001-7d0b-bcbe-2d3121799d0e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSMember_019c5518-b001-7d2b-b321-22d1dd611c5d" xlink:href="tlx-20251231.xsd#tlx_ARTMSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_ARTMSMember_019c5518-b001-7d2b-b321-22d1dd611c5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX101TxMember_019c5518-b001-7630-9cbc-4e49e91a58ac" xlink:href="tlx-20251231.xsd#tlx_TLX101TxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_TLX101TxMember_019c5518-b001-7630-9cbc-4e49e91a58ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TLX591PxIlluccixMember_019c7297-f012-7499-b8e6-02727da06a52" xlink:href="tlx-20251231.xsd#tlx_TLX591PxIlluccixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesDomain_019c5518-b001-7ae5-baab-175e63c7d345" xlink:to="loc_tlx_TLX591PxIlluccixMember_019c7297-f012-7499-b8e6-02727da06a52" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Goodwill_019c5518-b001-74c7-a2f8-f3d572c8186d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c5518-b001-79f4-8874-9d5704ace735" xlink:to="loc_ifrs-full_Goodwill_019c5518-b001-74c7-a2f8-f3d572c8186d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/IntangibleassetsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#IntangibleassetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/IntangibleassetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019c1294-4c69-78f2-9ef5-3416c88a92c6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:to="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019c1294-4c69-78f2-9ef5-3416c88a92c6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeAxis_019c1295-1963-7574-b7a3-5bc5619cd18c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfIntangibleAssetsTable_019c1294-4c69-78f2-9ef5-3416c88a92c6" xlink:to="loc_ifrs-full_RangeAxis_019c1295-1963-7574-b7a3-5bc5619cd18c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019c1295-1963-7574-b7a3-5bc5619cd18c_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_RangeAxis_019c1295-1963-7574-b7a3-5bc5619cd18c" xlink:to="loc_ifrs-full_RangeDomain_019c1295-1963-7574-b7a3-5bc5619cd18c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019c1295-1963-7048-9257-30ca6574a4b1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_RangeAxis_019c1295-1963-7574-b7a3-5bc5619cd18c" xlink:to="loc_ifrs-full_RangeDomain_019c1295-1963-7048-9257-30ca6574a4b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BottomOfRangeMember_019c1295-1963-7572-bdcd-c98591ae855d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BottomOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019c1295-1963-7048-9257-30ca6574a4b1" xlink:to="loc_ifrs-full_BottomOfRangeMember_019c1295-1963-7572-bdcd-c98591ae855d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TopOfRangeMember_019c1295-1963-7a4c-84a2-f4274a58e5b9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TopOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019c1295-1963-7048-9257-30ca6574a4b1" xlink:to="loc_ifrs-full_TopOfRangeMember_019c1295-1963-7a4c-84a2-f4274a58e5b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ImpairmentLossRecognisedInProfitOrLossGoodwill_019b0124-04a3-71ee-a5da-c7591a4671f4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ImpairmentLossRecognisedInProfitOrLossGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:to="loc_ifrs-full_ImpairmentLossRecognisedInProfitOrLossGoodwill_019b0124-04a3-71ee-a5da-c7591a4671f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DiscountedExpectedFutureCashFlowsPeriod_019b0124-04a3-7dcd-9b16-f7fc0b10a845" xlink:href="tlx-20251231.xsd#tlx_DiscountedExpectedFutureCashFlowsPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:to="loc_tlx_DiscountedExpectedFutureCashFlowsPeriod_019b0124-04a3-7dcd-9b16-f7fc0b10a845" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections_019c1290-5e77-7421-a61a-a22f9c575320" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:to="loc_ifrs-full_DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections_019c1290-5e77-7421-a61a-a22f9c575320" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfDiscountRatesUsedInCurrentEstimateOfValueInUse_019b0124-04a3-712f-9caa-0eb3c824bd51" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfDiscountRatesUsedInCurrentEstimateOfValueInUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c1294-9427-7d85-820b-43e59b5011ce" xlink:to="loc_ifrs-full_DescriptionOfDiscountRatesUsedInCurrentEstimateOfValueInUse_019b0124-04a3-712f-9caa-0eb3c824bd51" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/IntangibleassetsScheduleofImpactOfPossibleChangesInKeyAssumptionsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#IntangibleassetsScheduleofImpactOfPossibleChangesInKeyAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/IntangibleassetsScheduleofImpactOfPossibleChangesInKeyAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c21d4-9134-7d27-9001-16e93ad181c6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c21d4-9134-75d1-8865-c202d725f7b6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c21d4-9134-7d27-9001-16e93ad181c6" xlink:to="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c21d4-9134-75d1-8865-c202d725f7b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInKeyAssumptionAxis_019c21d4-9134-78a4-9ec3-c19d7c101685" xlink:href="tlx-20251231.xsd#tlx_ChangeInKeyAssumptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c21d4-9134-75d1-8865-c202d725f7b6" xlink:to="loc_tlx_ChangeInKeyAssumptionAxis_019c21d4-9134-78a4-9ec3-c19d7c101685" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-78a4-9ec3-c19d7c101685_default" xlink:href="tlx-20251231.xsd#tlx_ChangeInKeyAssumptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_ChangeInKeyAssumptionAxis_019c21d4-9134-78a4-9ec3-c19d7c101685" xlink:to="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-78a4-9ec3-c19d7c101685_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:href="tlx-20251231.xsd#tlx_ChangeInKeyAssumptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_ChangeInKeyAssumptionAxis_019c21d4-9134-78a4-9ec3-c19d7c101685" xlink:to="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_A2.5IncreaseInPostTaxDiscountRateMember_019c21d4-9134-72e0-adbc-5c1f1eff97c7" xlink:href="tlx-20251231.xsd#tlx_A2.5IncreaseInPostTaxDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:to="loc_tlx_A2.5IncreaseInPostTaxDiscountRateMember_019c21d4-9134-72e0-adbc-5c1f1eff97c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_A10DecreaseInProbabilityOfSuccessMember_019c21d4-9134-7fd5-ad5d-775c79bbd3d5" xlink:href="tlx-20251231.xsd#tlx_A10DecreaseInProbabilityOfSuccessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:to="loc_tlx_A10DecreaseInProbabilityOfSuccessMember_019c21d4-9134-7fd5-ad5d-775c79bbd3d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OneYearDelayInCommercializationMember_019c21d4-9134-7cb1-a6c3-95fc2ffddcf0" xlink:href="tlx-20251231.xsd#tlx_OneYearDelayInCommercializationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:to="loc_tlx_OneYearDelayInCommercializationMember_019c21d4-9134-7cb1-a6c3-95fc2ffddcf0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_A50ReductionInTerminalGrowthRateMember_019c21d4-9134-79c5-a34e-3f176ba821fe" xlink:href="tlx-20251231.xsd#tlx_A50ReductionInTerminalGrowthRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:to="loc_tlx_A50ReductionInTerminalGrowthRateMember_019c21d4-9134-79c5-a34e-3f176ba821fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_A10ReductionInFutureCashInflowsMember_019c21d4-9134-7188-943a-49a23fe8320c" xlink:href="tlx-20251231.xsd#tlx_A10ReductionInFutureCashInflowsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInKeyAssumptionDomain_019c21d4-9134-7751-ba7d-7f1af8304cce" xlink:to="loc_tlx_A10ReductionInFutureCashInflowsMember_019c21d4-9134-7188-943a-49a23fe8320c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesAxis_019c21d4-9134-79c6-90cd-5f79eebee028" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesTable_019c21d4-9134-75d1-8865-c202d725f7b6" xlink:to="loc_ifrs-full_ProductsAndServicesAxis_019c21d4-9134-79c6-90cd-5f79eebee028" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-79c6-90cd-5f79eebee028_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019c21d4-9134-79c6-90cd-5f79eebee028" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-79c6-90cd-5f79eebee028_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-7454-8edd-0ac069c8a461" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019c21d4-9134-79c6-90cd-5f79eebee028" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-7454-8edd-0ac069c8a461" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixTargetingTechnologyMember_019c21d4-9134-7037-bdc9-d8db64841b43" xlink:href="tlx-20251231.xsd#tlx_TelixTargetingTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-7454-8edd-0ac069c8a461" xlink:to="loc_tlx_TelixTargetingTechnologyMember_019c21d4-9134-7037-bdc9-d8db64841b43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019c21d4-9134-7053-8395-ebcaab7bc6bd" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019c21d4-9134-7454-8edd-0ac069c8a461" xlink:to="loc_tlx_RLSMember_019c21d4-9134-7053-8395-ebcaab7bc6bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInRecoverableAmountOfAssetOrCashGeneratingUnit_019c21d4-9134-7acb-882b-166efeb4eae1" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInRecoverableAmountOfAssetOrCashGeneratingUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesLineItems_019c21d4-9134-7d27-9001-16e93ad181c6" xlink:to="loc_tlx_IncreaseDecreaseInRecoverableAmountOfAssetOrCashGeneratingUnit_019c21d4-9134-7acb-882b-166efeb4eae1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b0124-04a3-77e6-9284-bbe1318b9d02" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b0124-04a3-77e6-9284-bbe1318b9d02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-77e6-9284-bbe1318b9d02_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-04a3-77e6-9284-bbe1318b9d02" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-77e6-9284-bbe1318b9d02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-7bfc-bd6e-bd7628ca9dc9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-04a3-77e6-9284-bbe1318b9d02" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-7bfc-bd6e-bd7628ca9dc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019b0124-04a3-7a63-ab0e-8dc8a65d7e0b" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-7bfc-bd6e-bd7628ca9dc9" xlink:to="loc_tlx_RLSMember_019b0124-04a3-7a63-ab0e-8dc8a65d7e0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ImaginAbIncMember_019be9bd-e206-7c48-b0c6-7bf87cdd1427" xlink:href="tlx-20251231.xsd#tlx_ImaginAbIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-7bfc-bd6e-bd7628ca9dc9" xlink:to="loc_tlx_ImaginAbIncMember_019be9bd-e206-7c48-b0c6-7bf87cdd1427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FAPTargetingMember_019be9be-484b-7542-9c46-d045dd292976" xlink:href="tlx-20251231.xsd#tlx_FAPTargetingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-04a3-7bfc-bd6e-bd7628ca9dc9" xlink:to="loc_tlx_FAPTargetingMember_019be9be-484b-7542-9c46-d045dd292976" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsAxis_019c5568-94dc-7cc9-ac5e-ea9315d96c27" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:to="loc_ifrs-full_ClassesOfAssetsAxis_019c5568-94dc-7cc9-ac5e-ea9315d96c27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7cc9-ac5e-ea9315d96c27_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019c5568-94dc-7cc9-ac5e-ea9315d96c27" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7cc9-ac5e-ea9315d96c27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7916-8e4a-37a77ebcae94" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019c5568-94dc-7cc9-ac5e-ea9315d96c27" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7916-8e4a-37a77ebcae94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodwillMember_019c5568-94dc-7b27-90e2-6c456aab6435" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7916-8e4a-37a77ebcae94" xlink:to="loc_ifrs-full_GoodwillMember_019c5568-94dc-7b27-90e2-6c456aab6435" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WorkingCapitalMember_019c5568-94dc-79bb-8153-20325074f83d" xlink:href="tlx-20251231.xsd#tlx_WorkingCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7916-8e4a-37a77ebcae94" xlink:to="loc_tlx_WorkingCapitalMember_019c5568-94dc-79bb-8153-20325074f83d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxAssetMember_019c5568-94dc-7368-9c25-0a74717b1c7f" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019c5568-94dc-7916-8e4a-37a77ebcae94" xlink:to="loc_tlx_DeferredTaxAssetMember_019c5568-94dc-7368-9c25-0a74717b1c7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e1-ef88-7c90-997f-dae4eab0862e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e1-ef88-7c90-997f-dae4eab0862e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-7c90-997f-dae4eab0862e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e1-ef88-7c90-997f-dae4eab0862e" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-7c90-997f-dae4eab0862e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-724e-a62c-179b72071155" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e1-ef88-7c90-997f-dae4eab0862e" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-724e-a62c-179b72071155" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BrandNamesMember_019c63e1-ef88-75c0-b34e-767eed386b1b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BrandNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-724e-a62c-179b72071155" xlink:to="loc_ifrs-full_BrandNamesMember_019c63e1-ef88-75c0-b34e-767eed386b1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LicencesMember_019c63e2-3440-7fd1-a04f-c5d89a8d2ee8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LicencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e1-ef88-724e-a62c-179b72071155" xlink:to="loc_ifrs-full_LicencesMember_019c63e2-3440-7fd1-a04f-c5d89a8d2ee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019c7601-84e2-7b2e-b085-99b9e45a9cd6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b0124-04a3-7d87-9e97-e005896db4ba" xlink:to="loc_srt_RangeAxis_019c7601-84e2-7b2e-b085-99b9e45a9cd6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c7601-84e2-7b2e-b085-99b9e45a9cd6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019c7601-84e2-7b2e-b085-99b9e45a9cd6" xlink:to="loc_srt_RangeMember_019c7601-84e2-7b2e-b085-99b9e45a9cd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c7601-84e2-7515-94ff-8cc773100675" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019c7601-84e2-7b2e-b085-99b9e45a9cd6" xlink:to="loc_srt_RangeMember_019c7601-84e2-7515-94ff-8cc773100675" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019c7601-84e2-7b1e-b45f-872f4727000f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019c7601-84e2-7515-94ff-8cc773100675" xlink:to="loc_srt_MaximumMember_019c7601-84e2-7b1e-b45f-872f4727000f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b43be-6f23-7b45-bcd4-3de38e215758" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b43be-6f23-7b45-bcd4-3de38e215758" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashTransferred_019b43be-6f23-7177-ac85-e191f3ebcfde" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_CashTransferred_019b43be-6f23-7177-ac85-e191f3ebcfde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019b43be-6f23-79c5-b9dc-aec92ea40889" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019b43be-6f23-79c5-b9dc-aec92ea40889" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration_019c5568-94dc-7984-9b18-5f24621bc67a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration_019c5568-94dc-7984-9b18-5f24621bc67a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueOfAcquiree_019b43be-987e-7ee9-a254-9d83a32da2c0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueOfAcquiree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_RevenueOfAcquiree_019b43be-987e-7ee9-a254-9d83a32da2c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossOfAcquiree_019b43be-987e-7442-9cb4-e556e8e2e03e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossOfAcquiree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_ProfitLossOfAcquiree_019b43be-987e-7442-9cb4-e556e8e2e03e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueOfCombinedEntity_019b43be-987e-7927-878a-32fb392176f6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueOfCombinedEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_RevenueOfCombinedEntity_019b43be-987e-7927-878a-32fb392176f6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossOfCombinedEntity_019c12bd-09ed-7810-b1e9-9ffce1a0ca8c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossOfCombinedEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_ProfitLossOfCombinedEntity_019c12bd-09ed-7810-b1e9-9ffce1a0ca8c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EquityInterestsOfAcquirer_019be9bd-e206-7937-8805-2a06372cc4ef" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EquityInterestsOfAcquirer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_EquityInterestsOfAcquirer_019be9bd-e206-7937-8805-2a06372cc4ef" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable_019be9bd-e206-7a1f-b245-ed069e6fabdf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable_019be9bd-e206-7a1f-b245-ed069e6fabdf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ParValuePerShare_019be9bd-e206-76c1-8f32-ac1d5e3d74b9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ParValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_ParValuePerShare_019be9bd-e206-76c1-8f32-ac1d5e3d74b9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019be9bd-e206-7a61-8c5d-900f6057ba3c" xlink:href="tlx-20251231.xsd#tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019be9bd-e206-7a61-8c5d-900f6057ba3c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MaximumDeferredConsiderationRecognisedAsOfAcquisitionDate_019c12c9-7f82-7c73-bc89-30377e678665" xlink:href="tlx-20251231.xsd#tlx_MaximumDeferredConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_MaximumDeferredConsiderationRecognisedAsOfAcquisitionDate_019c12c9-7f82-7c73-bc89-30377e678665" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BusinessCombinationIndemnityPeriod_019be9bd-e206-7513-8d12-f4c177e0c3e3" xlink:href="tlx-20251231.xsd#tlx_BusinessCombinationIndemnityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_BusinessCombinationIndemnityPeriod_019be9bd-e206-7513-8d12-f4c177e0c3e3" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ContingentLiabilitiesRecognisedAsOfAcquisitionDate_019be9bd-e206-7d4f-9f0c-c4767e94b999" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ContingentLiabilitiesRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_ContingentLiabilitiesRecognisedAsOfAcquisitionDate_019be9bd-e206-7d4f-9f0c-c4767e94b999" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfProductsDeveloped_019c12cb-1160-72e0-a837-b9bfae04493a" xlink:href="tlx-20251231.xsd#tlx_NumberOfProductsDeveloped"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_NumberOfProductsDeveloped_019c12cb-1160-72e0-a837-b9bfae04493a" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PerformanceRightsIssuedAsOfAcquisitionDate_019c63e8-b05f-770e-a90b-a69205480f34" xlink:href="tlx-20251231.xsd#tlx_PerformanceRightsIssuedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_PerformanceRightsIssuedAsOfAcquisitionDate_019c63e8-b05f-770e-a90b-a69205480f34" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63e0-dcaf-7d24-93a1-92b3aa7b5fa9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63e0-dcaf-7d24-93a1-92b3aa7b5fa9" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UpfrontCashTransferredAsOfAcquisitionDate_019be9be-484b-77b1-9fb7-41aa030473df" xlink:href="tlx-20251231.xsd#tlx_UpfrontCashTransferredAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_UpfrontCashTransferredAsOfAcquisitionDate_019be9be-484b-77b1-9fb7-41aa030473df" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CashTransferredUponSigning_019c552f-43e6-7bdc-9280-4a2d97d1924b" xlink:href="tlx-20251231.xsd#tlx_CashTransferredUponSigning"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_CashTransferredUponSigning_019c552f-43e6-7bdc-9280-4a2d97d1924b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredConsiderationUnderLicenseAgreementRecognisedAsOfAcquisitionDate_019be9be-484b-7921-8ceb-6079d5e9adab" xlink:href="tlx-20251231.xsd#tlx_DeferredConsiderationUnderLicenseAgreementRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b0124-04a3-728d-88df-98fcae220a11" xlink:to="loc_tlx_DeferredConsiderationUnderLicenseAgreementRecognisedAsOfAcquisitionDate_019be9be-484b-7921-8ceb-6079d5e9adab" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforRLSDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsScheduleofConsiderationPaidforRLSDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforRLSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b43bc-318d-7247-9507-10a6bca15e76" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b43bc-318d-7247-9507-10a6bca15e76" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b43bc-318d-79fd-8f1e-443844af253f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b43bc-318d-7247-9507-10a6bca15e76" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b43bc-318d-79fd-8f1e-443844af253f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b43bc-318d-79fd-8f1e-443844af253f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b43bc-318d-79fd-8f1e-443844af253f" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b43bc-318d-79fd-8f1e-443844af253f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b43bc-318d-75d4-ade0-01c35e2d1e40" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b43bc-318d-79fd-8f1e-443844af253f" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b43bc-318d-75d4-ade0-01c35e2d1e40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019b43dd-ec2a-7a8b-aa0f-952f42eb0d6b" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b43bc-318d-75d4-ade0-01c35e2d1e40" xlink:to="loc_tlx_RLSMember_019b43dd-ec2a-7a8b-aa0f-952f42eb0d6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashTransferred_019b43bc-318d-7639-a4d5-c5b704493542" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_CashTransferred_019b43bc-318d-7639-a4d5-c5b704493542" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019b43bc-318d-7e9b-bfe9-a38a149a572f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019b43bc-318d-7e9b-bfe9-a38a149a572f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b43bc-318d-798f-9ede-6e1b5954633d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b43bc-318d-798f-9ede-6e1b5954633d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashAndCashEquivalentsRecognisedAsOfAcquisitionDate_019b43bc-318d-72cf-9026-26bb8ea21742" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalentsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_CashAndCashEquivalentsRecognisedAsOfAcquisitionDate_019b43bc-318d-72cf-9026-26bb8ea21742" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TradeAndOtherReceivablesRecognizedAsOfAcquisitionDate_019b43bc-318d-75b1-af7f-d94b26f63ae9" xlink:href="tlx-20251231.xsd#tlx_TradeAndOtherReceivablesRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_TradeAndOtherReceivablesRecognizedAsOfAcquisitionDate_019b43bc-318d-75b1-af7f-d94b26f63ae9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentAssetsRecognisedAsOfAcquisitionDate_019b441c-e3d5-7548-8239-f5105d860a31" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentAssetsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_CurrentAssetsRecognisedAsOfAcquisitionDate_019b441c-e3d5-7548-8239-f5105d860a31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_InventoryRecognisedAsOfAcquisitionDate_019b43e3-6fee-7d7f-9cf4-5f42dd068567" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InventoryRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_InventoryRecognisedAsOfAcquisitionDate_019b43e3-6fee-7d7f-9cf4-5f42dd068567" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate_019b43bc-318d-7ec9-8fb8-13cb3a9bce60" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate_019b43bc-318d-7ec9-8fb8-13cb3a9bce60" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c6a5b-e9d1-725f-9f7d-7b3a724e0df0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c6a5b-e9d1-725f-9f7d-7b3a724e0df0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InvestmentInSubLeaseRecognizedAsOfAcquisitionDate_019b441f-ebee-764f-9c1f-aa06de5a3e1c" xlink:href="tlx-20251231.xsd#tlx_InvestmentInSubLeaseRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_InvestmentInSubLeaseRecognizedAsOfAcquisitionDate_019b441f-ebee-764f-9c1f-aa06de5a3e1c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate_019b43bc-318d-7ab3-8e6a-18264b83902b" xlink:href="tlx-20251231.xsd#tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate_019b43bc-318d-7ab3-8e6a-18264b83902b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TradeAndOtherPayablesAsOfAcquisitionDate_019b43dc-5e3c-782e-806e-5e6c62970ba2" xlink:href="tlx-20251231.xsd#tlx_TradeAndOtherPayablesAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_TradeAndOtherPayablesAsOfAcquisitionDate_019b43dc-5e3c-782e-806e-5e6c62970ba2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentOrDeferredConsiderationAsOfAcquisitionDate_019bfcf9-6eb8-7436-981c-99bcf16d7fef" xlink:href="tlx-20251231.xsd#tlx_ContingentOrDeferredConsiderationAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_ContingentOrDeferredConsiderationAsOfAcquisitionDate_019bfcf9-6eb8-7436-981c-99bcf16d7fef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate_019b43bc-318d-7acc-9ec6-7f6c8584f4f6" xlink:href="tlx-20251231.xsd#tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate_019b43bc-318d-7acc-9ec6-7f6c8584f4f6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b43bc-318d-702b-b800-8d903828e9d9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4422-7bf1-7d22-bc00-a468c5e7af99" xlink:to="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b43bc-318d-702b-b800-8d903828e9d9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentCustomerRelationships_019bea33-beee-7125-9f56-b02f122575a0" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentCustomerRelationships"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentCustomerRelationships_019bea33-beee-7125-9f56-b02f122575a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentBrandName_019b43bc-318d-7a93-b4a9-1adb56bc5f5e" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentBrandName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentBrandName_019b43bc-318d-7a93-b4a9-1adb56bc5f5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentRadioPharmacyLicenses_019b4424-e524-7f4c-9d52-7065b5967433" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentRadioPharmacyLicenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentRadioPharmacyLicenses_019b4424-e524-7f4c-9d52-7065b5967433" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentDeferredTaxLiability_019b43bc-318d-780e-a208-e361774d7d4a" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentDeferredTaxLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentDeferredTaxLiability_019b43bc-318d-780e-a208-e361774d7d4a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentDeferredTaxAssets_019b4427-b371-7fe5-ae39-735fe3068547" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentDeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentDeferredTaxAssets_019b4427-b371-7fe5-ae39-735fe3068547" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueAdjustmentsRecognizedAsOfAcquisitionDate_019b43bc-318d-75e5-a1cd-b92925783f38" xlink:href="tlx-20251231.xsd#tlx_FairValueAdjustmentsRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AdditionalDisclosuresForAmountsRecognisedAsOfAcquisitionDateForEachMajorClassOfAssetsAcquiredAndLiabilitiesAssumedAbstract_019b4423-03f8-7b3b-b705-bd6e348556ed" xlink:to="loc_tlx_FairValueAdjustmentsRecognizedAsOfAcquisitionDate_019b43bc-318d-75e5-a1cd-b92925783f38" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodwillRecognisedAsOfAcquisitionDate_019b43bc-318d-7e26-b646-36a171170bb6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodwillRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b43bc-318d-708c-b6c4-228a90a7f053" xlink:to="loc_ifrs-full_GoodwillRecognisedAsOfAcquisitionDate_019b43bc-318d-7e26-b646-36a171170bb6" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsScheduleofUsefulEconomicLivesofAcquisitionofRLSDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsScheduleofUsefulEconomicLivesofAcquisitionofRLSDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsScheduleofUsefulEconomicLivesofAcquisitionofRLSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019be052-ab6c-71be-9311-37d2e8873f05" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019be052-ab6c-7224-9b49-d8707f7e864c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019be052-ab6c-71be-9311-37d2e8873f05" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019be052-ab6c-7224-9b49-d8707f7e864c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019be052-ab6c-7bb1-b09f-2e8de20946b9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019be052-ab6c-7224-9b49-d8707f7e864c" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019be052-ab6c-7bb1-b09f-2e8de20946b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019be052-ab6c-7bb1-b09f-2e8de20946b9_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019be052-ab6c-7bb1-b09f-2e8de20946b9" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019be052-ab6c-7bb1-b09f-2e8de20946b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019be052-ab6c-72f4-8ef7-f18bd99c6c51" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019be052-ab6c-7bb1-b09f-2e8de20946b9" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019be052-ab6c-72f4-8ef7-f18bd99c6c51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSMember_019be052-ab6c-7a9c-b398-4981fd9c817c" xlink:href="tlx-20251231.xsd#tlx_RLSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019be052-ab6c-72f4-8ef7-f18bd99c6c51" xlink:to="loc_tlx_RLSMember_019be052-ab6c-7a9c-b398-4981fd9c817c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019be054-678f-7d75-b174-e84a3660b8f1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019be052-ab6c-7224-9b49-d8707f7e864c" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019be054-678f-7d75-b174-e84a3660b8f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-7d75-b174-e84a3660b8f1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019be054-678f-7d75-b174-e84a3660b8f1" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-7d75-b174-e84a3660b8f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-76bd-92e8-020b0cb24258" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019be054-678f-7d75-b174-e84a3660b8f1" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-76bd-92e8-020b0cb24258" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CustomerrelatedIntangibleAssetsMember_019be056-a4f3-7e7e-8ded-b87409792907" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CustomerrelatedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-76bd-92e8-020b0cb24258" xlink:to="loc_ifrs-full_CustomerrelatedIntangibleAssetsMember_019be056-a4f3-7e7e-8ded-b87409792907" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BrandNamesMember_019be057-90cf-79ec-808c-af739a83fd46" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BrandNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-76bd-92e8-020b0cb24258" xlink:to="loc_ifrs-full_BrandNamesMember_019be057-90cf-79ec-808c-af739a83fd46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LicencesMember_019be058-dafc-75fe-b0eb-b6193e25ef69" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LicencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019be054-678f-76bd-92e8-020b0cb24258" xlink:to="loc_ifrs-full_LicencesMember_019be058-dafc-75fe-b0eb-b6193e25ef69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill_019be052-ab6c-77a8-8af6-88c0815b7ba0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019be052-ab6c-71be-9311-37d2e8873f05" xlink:to="loc_ifrs-full_UsefulLifeMeasuredAsPeriodOfTimeIntangibleAssetsOtherThanGoodwill_019be052-ab6c-77a8-8af6-88c0815b7ba0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforImaginAbIncDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsScheduleofConsiderationPaidforImaginAbIncDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforImaginAbIncDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b445d-faeb-7082-a175-b8d081fad84d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b445d-faeb-7082-a175-b8d081fad84d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b445d-faeb-79fc-8dcb-916f71380156" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b445d-faeb-7082-a175-b8d081fad84d" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b445d-faeb-79fc-8dcb-916f71380156" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b445d-faeb-79fc-8dcb-916f71380156_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b445d-faeb-79fc-8dcb-916f71380156" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b445d-faeb-79fc-8dcb-916f71380156_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b445d-faeb-707a-a1b4-f592a6d72087" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b445d-faeb-79fc-8dcb-916f71380156" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b445d-faeb-707a-a1b4-f592a6d72087" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ImaginAbIncMember_019b4469-12e8-74a1-a2c1-8702949a2011" xlink:href="tlx-20251231.xsd#tlx_ImaginAbIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b445d-faeb-707a-a1b4-f592a6d72087" xlink:to="loc_tlx_ImaginAbIncMember_019b4469-12e8-74a1-a2c1-8702949a2011" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63df-6ce4-74b3-a369-99f77a16f69a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b445d-faeb-7082-a175-b8d081fad84d" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63df-6ce4-74b3-a369-99f77a16f69a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-74b3-a369-99f77a16f69a_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63df-6ce4-74b3-a369-99f77a16f69a" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-74b3-a369-99f77a16f69a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-7b4a-8d3d-a5e40ead93c5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63df-6ce4-74b3-a369-99f77a16f69a" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-7b4a-8d3d-a5e40ead93c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BrandNamesMember_019c63df-f587-725d-a261-7e7fbe631dcb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BrandNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-7b4a-8d3d-a5e40ead93c5" xlink:to="loc_ifrs-full_BrandNamesMember_019c63df-f587-725d-a261-7e7fbe631dcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LicencesMember_019c63df-c134-7193-a847-17bb940a0d88" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LicencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63df-6ce4-7b4a-8d3d-a5e40ead93c5" xlink:to="loc_ifrs-full_LicencesMember_019c63df-c134-7193-a847-17bb940a0d88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashTransferred_019b445d-faeb-77ac-899b-03a93fed0f2b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_CashTransferred_019b445d-faeb-77ac-899b-03a93fed0f2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PerformanceRightsIssuedAsOfAcquisitionDate_019b445e-86d8-7a86-b37c-41c5afdabef5" xlink:href="tlx-20251231.xsd#tlx_PerformanceRightsIssuedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_tlx_PerformanceRightsIssuedAsOfAcquisitionDate_019b445e-86d8-7a86-b37c-41c5afdabef5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EquityInterestsOfAcquirer_019b445d-faeb-7ddc-925c-f77a4a3d3754" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EquityInterestsOfAcquirer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_EquityInterestsOfAcquirer_019b445d-faeb-7ddc-925c-f77a4a3d3754" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_AcquisitionRelatedCosts_019b4462-8520-7a21-abb6-e2af8499ae28" xlink:href="tlx-20251231.xsd#tlx_AcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_tlx_AcquisitionRelatedCosts_019b4462-8520-7a21-abb6-e2af8499ae28" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019b445d-faeb-71d7-a468-4a3d51e28052" xlink:href="tlx-20251231.xsd#tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019b445d-faeb-71d7-a468-4a3d51e28052" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b445d-faeb-7542-994c-dc2566060ea7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b445d-faeb-7542-994c-dc2566060ea7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate_019b445d-faeb-76b6-b99d-9d16f41ad68e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate_019b445d-faeb-76b6-b99d-9d16f41ad68e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate_019b445d-faeb-73a0-9413-b4eed64acaba" xlink:href="tlx-20251231.xsd#tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_tlx_RightOfUseAssetsRecognizedAsOfAcquisitionDate_019b445d-faeb-73a0-9413-b4eed64acaba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63df-063b-7010-9b62-d545d0b9bfa9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63df-063b-7010-9b62-d545d0b9bfa9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate_019b445d-faeb-7b23-89cb-98cb42631907" xlink:href="tlx-20251231.xsd#tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_tlx_LeaseLiabilitiesRecognizedAsOfAcquisitionDate_019b445d-faeb-7b23-89cb-98cb42631907" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b445d-faeb-788a-b2d1-05910571c6fc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b445d-faeb-7cf2-bbc1-3c2091aed93e" xlink:to="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b445d-faeb-788a-b2d1-05910571c6fc" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforFAPTargetingDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsScheduleofConsiderationPaidforFAPTargetingDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsScheduleofConsiderationPaidforFAPTargetingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b448e-83fc-7a43-960e-032800d21b70" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b448e-83fc-7a43-960e-032800d21b70" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b448e-83fc-78a7-9923-1cf8f919b209" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b448e-83fc-7a43-960e-032800d21b70" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b448e-83fc-78a7-9923-1cf8f919b209" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b448e-83fc-78a7-9923-1cf8f919b209_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b448e-83fc-78a7-9923-1cf8f919b209" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b448e-83fc-78a7-9923-1cf8f919b209_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b448e-83fc-77cc-a810-c0e810e58748" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b448e-83fc-78a7-9923-1cf8f919b209" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b448e-83fc-77cc-a810-c0e810e58748" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FAPTargetingMember_019b448e-83fc-7b94-afa0-d182aef55d81" xlink:href="tlx-20251231.xsd#tlx_FAPTargetingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b448e-83fc-77cc-a810-c0e810e58748" xlink:to="loc_tlx_FAPTargetingMember_019b448e-83fc-7b94-afa0-d182aef55d81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e3-fdcd-7a5d-8257-2eaeead87d8a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019b448e-83fc-7a43-960e-032800d21b70" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e3-fdcd-7a5d-8257-2eaeead87d8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-7a5d-8257-2eaeead87d8a_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e3-fdcd-7a5d-8257-2eaeead87d8a" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-7a5d-8257-2eaeead87d8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-780c-b07a-10cded466a01" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillAxis_019c63e3-fdcd-7a5d-8257-2eaeead87d8a" xlink:to="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-780c-b07a-10cded466a01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BrandNamesMember_019c63e3-fdcd-74de-b1a3-2f7e219fcff1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BrandNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-780c-b07a-10cded466a01" xlink:to="loc_ifrs-full_BrandNamesMember_019c63e3-fdcd-74de-b1a3-2f7e219fcff1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LicencesMember_019c63e3-fdcd-7bec-a84b-d96bc6c1c736" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LicencesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfIntangibleAssetsOtherThanGoodwillDomain_019c63e3-fdcd-780c-b07a-10cded466a01" xlink:to="loc_ifrs-full_LicencesMember_019c63e3-fdcd-7bec-a84b-d96bc6c1c736" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashTransferred_019b448e-83fc-7ae2-a1af-66d221cfcb22" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_ifrs-full_CashTransferred_019b448e-83fc-7ae2-a1af-66d221cfcb22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_AcquisitionRelatedCosts_019b448e-83fc-7399-acc1-750e605dd759" xlink:href="tlx-20251231.xsd#tlx_AcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_tlx_AcquisitionRelatedCosts_019b448e-83fc-7399-acc1-750e605dd759" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019b448e-83fc-780e-baf3-4e9fe9db35c8" xlink:href="tlx-20251231.xsd#tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_tlx_DeferredConsiderationRecognisedAsOfAcquisitionDate_019b448e-83fc-780e-baf3-4e9fe9db35c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b448e-83fc-7624-97a4-b54855a3a872" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred_019b448e-83fc-7624-97a4-b54855a3a872" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63e2-c2ae-79e4-86a6-69b77a9eb5af" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_ifrs-full_IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate_019c63e2-c2ae-79e4-86a6-69b77a9eb5af" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b448e-83fc-74b8-b98d-adf3c7603657" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019b448e-83fc-71ce-8353-d6d4c9cf406f" xlink:to="loc_ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed_019b448e-83fc-74b8-b98d-adf3c7603657" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/AcquisitionsARTMSMeasurementperiodadjustmentsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#AcquisitionsARTMSMeasurementperiodadjustmentsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/AcquisitionsARTMSMeasurementperiodadjustmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019c54c5-54cf-7d0f-b5b0-26197facee9b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019c54c5-54cf-7abc-86d8-8870b748ee73" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019c54c5-54cf-7d0f-b5b0-26197facee9b" xlink:to="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019c54c5-54cf-7abc-86d8-8870b748ee73" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019c54c5-54cf-70cd-9edf-abefe71428ab" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019c54c5-54cf-7abc-86d8-8870b748ee73" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019c54c5-54cf-70cd-9edf-abefe71428ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c54c5-54cf-70cd-9edf-abefe71428ab_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c54c5-54cf-70cd-9edf-abefe71428ab" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c54c5-54cf-70cd-9edf-abefe71428ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019c54c5-54cf-7002-871c-343421b36363" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019c54c5-54cf-70cd-9edf-abefe71428ab" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019c54c5-54cf-7002-871c-343421b36363" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSIncMember_019c54c6-3768-7647-88cd-fbb0eef2b188" xlink:href="tlx-20251231.xsd#tlx_ARTMSIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019c54c5-54cf-7002-871c-343421b36363" xlink:to="loc_tlx_ARTMSIncMember_019c54c6-3768-7647-88cd-fbb0eef2b188" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsAxis_019c54c6-f81a-7515-b891-bace9e78bee5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019c54c5-54cf-7abc-86d8-8870b748ee73" xlink:to="loc_ifrs-full_ClassesOfAssetsAxis_019c54c6-f81a-7515-b891-bace9e78bee5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7515-b891-bace9e78bee5_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019c54c6-f81a-7515-b891-bace9e78bee5" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7515-b891-bace9e78bee5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7728-8442-3d8a9bb2a8c8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019c54c6-f81a-7515-b891-bace9e78bee5" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7728-8442-3d8a9bb2a8c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IntangibleAssetsOtherThanGoodwillMember_019c54ca-278f-7837-a3eb-af5ed95c283d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IntangibleAssetsOtherThanGoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7728-8442-3d8a9bb2a8c8" xlink:to="loc_ifrs-full_IntangibleAssetsOtherThanGoodwillMember_019c54ca-278f-7837-a3eb-af5ed95c283d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GoodwillMember_019c54c8-dfb7-7c47-8de5-d301eb46b039" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019c54c6-f81a-7728-8442-3d8a9bb2a8c8" xlink:to="loc_ifrs-full_GoodwillMember_019c54c8-dfb7-7c47-8de5-d301eb46b039" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfLiabilitiesAxis_019c54c7-3520-70bf-bde5-d57af06aac3b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfLiabilitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsTable_019c54c5-54cf-7abc-86d8-8870b748ee73" xlink:to="loc_ifrs-full_ClassesOfLiabilitiesAxis_019c54c7-3520-70bf-bde5-d57af06aac3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfLiabilitiesDomain_019c54c7-3520-70bf-bde5-d57af06aac3b_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfLiabilitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfLiabilitiesAxis_019c54c7-3520-70bf-bde5-d57af06aac3b" xlink:to="loc_ifrs-full_ClassesOfLiabilitiesDomain_019c54c7-3520-70bf-bde5-d57af06aac3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfLiabilitiesDomain_019c54c7-3520-7730-8259-a23edb84f712" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfLiabilitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfLiabilitiesAxis_019c54c7-3520-70bf-bde5-d57af06aac3b" xlink:to="loc_ifrs-full_ClassesOfLiabilitiesDomain_019c54c7-3520-7730-8259-a23edb84f712" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DeferredTaxLiabilityMember_019c54c7-c37c-7c10-8f0f-efd6f460ba9a" xlink:href="tlx-20251231.xsd#tlx_DeferredTaxLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfLiabilitiesDomain_019c54c7-3520-7730-8259-a23edb84f712" xlink:to="loc_tlx_DeferredTaxLiabilityMember_019c54c7-c37c-7c10-8f0f-efd6f460ba9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration_019c54c5-54cf-7b0e-85a8-909662749879" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfBusinessCombinationsLineItems_019c54c5-54cf-7d0f-b5b0-26197facee9b" xlink:to="loc_ifrs-full_MeasurementPeriodAdjustmentsRecognisedForParticularAssetsLiabilitiesNoncontrollingInterestsOrItemsOfConsideration_019c54c5-54cf-7b0e-85a8-909662749879" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsScheduleofMaturityAnalysisforBorrowingsFromLendersDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsScheduleofMaturityAnalysisforBorrowingsFromLendersDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsScheduleofMaturityAnalysisforBorrowingsFromLendersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-76dc-8309-dc4314518751" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-701e-9aa8-99687d84325a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-76dc-8309-dc4314518751" xlink:to="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-701e-9aa8-99687d84325a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-73a0-af3f-c21a55cc925b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-701e-9aa8-99687d84325a" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-73a0-af3f-c21a55cc925b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-73a0-af3f-c21a55cc925b_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-73a0-af3f-c21a55cc925b" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-73a0-af3f-c21a55cc925b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-73a0-af3f-c21a55cc925b" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TheHongkongAndShanghaiBankingCorporationLimitedAsTheTrusteeForConvertibleBondHoldersMember_019b0124-055c-7c63-a607-62d7be29505e" xlink:href="tlx-20251231.xsd#tlx_TheHongkongAndShanghaiBankingCorporationLimitedAsTheTrusteeForConvertibleBondHoldersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:to="loc_tlx_TheHongkongAndShanghaiBankingCorporationLimitedAsTheTrusteeForConvertibleBondHoldersMember_019b0124-055c-7c63-a607-62d7be29505e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IMBCGroupMember_019b0124-055c-7896-b6b9-9fc6f6f16ae8" xlink:href="tlx-20251231.xsd#tlx_IMBCGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:to="loc_tlx_IMBCGroupMember_019b0124-055c-7896-b6b9-9fc6f6f16ae8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BNPParibasMember_019b0124-055c-7ac1-b38e-727d8501689a" xlink:href="tlx-20251231.xsd#tlx_BNPParibasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:to="loc_tlx_BNPParibasMember_019b0124-055c-7ac1-b38e-727d8501689a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_HSBCBankAustraliaLtdMember_019b0124-055c-77a7-adfa-7139db532a7b" xlink:href="tlx-20251231.xsd#tlx_HSBCBankAustraliaLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-70fd-b4a5-9de14514634a" xlink:to="loc_tlx_HSBCBankAustraliaLtdMember_019b0124-055c-77a7-adfa-7139db532a7b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:href="tlx-20251231.xsd#tlx_BorrowingsLenderAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-76dc-8309-dc4314518751" xlink:to="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019b0124-055c-7c64-8452-50b7d337369f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_ifrs-full_Borrowings_019b0124-055c-7c64-8452-50b7d337369f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ShorttermBorrowings_019b0124-055c-79da-869e-b07b0af9a112" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShorttermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_ifrs-full_ShorttermBorrowings_019b0124-055c-79da-869e-b07b0af9a112" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LongtermBorrowings_019b0124-055c-715a-bc46-0d17c6bb3602" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LongtermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_ifrs-full_LongtermBorrowings_019b0124-055c-715a-bc46-0d17c6bb3602" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingFacilitiesMaximumBorrowingCapacity_019b0124-055c-7d9b-8264-7f8aed18a5ea" xlink:href="tlx-20251231.xsd#tlx_BorrowingFacilitiesMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_tlx_BorrowingFacilitiesMaximumBorrowingCapacity_019b0124-055c-7d9b-8264-7f8aed18a5ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsOverPayments_019c5555-5283-7d79-b938-1a4e2e8682fc" xlink:href="tlx-20251231.xsd#tlx_BorrowingsOverPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_tlx_BorrowingsOverPayments_019c5555-5283-7d79-b938-1a4e2e8682fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CurrentBorrowingsOverPayments_019c5556-312f-78e0-b3d1-47caa35c74d7" xlink:href="tlx-20251231.xsd#tlx_CurrentBorrowingsOverPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_tlx_CurrentBorrowingsOverPayments_019c5556-312f-78e0-b3d1-47caa35c74d7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NonCurrentBorrowingsOverPayments_019c5555-b6e2-7363-9873-ec382a11e1d3" xlink:href="tlx-20251231.xsd#tlx_NonCurrentBorrowingsOverPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_tlx_NonCurrentBorrowingsOverPayments_019c5555-b6e2-7363-9873-ec382a11e1d3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsMaturityTerm_019c32d1-c97f-743e-a986-84ed6f5069a2" xlink:href="tlx-20251231.xsd#tlx_BorrowingsMaturityTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_BorrowingsLenderAbstract_019b0124-055c-79b1-9771-2de034c96951" xlink:to="loc_tlx_BorrowingsMaturityTerm_019c32d1-c97f-743e-a986-84ed6f5069a2" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsBankLoansDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsBankLoansDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsBankLoansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7b6c-8cd9-86cf115c0256" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7b6c-8cd9-86cf115c0256" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesAxis_019b0124-055c-7458-a3ee-25b7ed3d946e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7b6c-8cd9-86cf115c0256" xlink:to="loc_ifrs-full_ProductsAndServicesAxis_019b0124-055c-7458-a3ee-25b7ed3d946e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-055c-7458-a3ee-25b7ed3d946e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-055c-7458-a3ee-25b7ed3d946e" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-055c-7458-a3ee-25b7ed3d946e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProductsAndServicesDomain_019b0124-055c-7fdc-90a2-912001cd09db" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ProductsAndServicesAxis_019b0124-055c-7458-a3ee-25b7ed3d946e" xlink:to="loc_ifrs-full_ProductsAndServicesDomain_019b0124-055c-7fdc-90a2-912001cd09db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RadiopharmaceuticalProductionFacilityMember_019b0124-055c-7d2c-afc0-87bd7de31ccc" xlink:href="tlx-20251231.xsd#tlx_RadiopharmaceuticalProductionFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ProductsAndServicesDomain_019b0124-055c-7fdc-90a2-912001cd09db" xlink:to="loc_tlx_RadiopharmaceuticalProductionFacilityMember_019b0124-055c-7d2c-afc0-87bd7de31ccc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7115-875f-d843e93913a5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7b6c-8cd9-86cf115c0256" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7115-875f-d843e93913a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7115-875f-d843e93913a5_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7115-875f-d843e93913a5" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7115-875f-d843e93913a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-78c5-a8d9-68aab60f8773" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7115-875f-d843e93913a5" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-78c5-a8d9-68aab60f8773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BNPParibasAndIMBCGroupMember_019b0124-055c-7e1b-ab1d-54850e88771e" xlink:href="tlx-20251231.xsd#tlx_BNPParibasAndIMBCGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-78c5-a8d9-68aab60f8773" xlink:to="loc_tlx_BNPParibasAndIMBCGroupMember_019b0124-055c-7e1b-ab1d-54850e88771e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BNPParibasMember_019b0124-055c-7ced-9f9b-af97d06fe8b3" xlink:href="tlx-20251231.xsd#tlx_BNPParibasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-78c5-a8d9-68aab60f8773" xlink:to="loc_tlx_BNPParibasMember_019b0124-055c-7ced-9f9b-af97d06fe8b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeAxis_019b0124-055c-757e-adab-e1afcc4df2c3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7b6c-8cd9-86cf115c0256" xlink:to="loc_ifrs-full_RangeAxis_019b0124-055c-757e-adab-e1afcc4df2c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-055c-757e-adab-e1afcc4df2c3_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_RangeAxis_019b0124-055c-757e-adab-e1afcc4df2c3" xlink:to="loc_ifrs-full_RangeDomain_019b0124-055c-757e-adab-e1afcc4df2c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RangeDomain_019b0124-055c-79b3-ba18-987fefff3bec" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_RangeAxis_019b0124-055c-757e-adab-e1afcc4df2c3" xlink:to="loc_ifrs-full_RangeDomain_019b0124-055c-79b3-ba18-987fefff3bec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TopOfRangeMember_019b0124-055c-7cb8-ad2d-fc92da8dbc0e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TopOfRangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_RangeDomain_019b0124-055c-79b3-ba18-987fefff3bec" xlink:to="loc_ifrs-full_TopOfRangeMember_019b0124-055c-7cb8-ad2d-fc92da8dbc0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfLoanAgreements_019b0124-055c-7092-a732-214729efa327" xlink:href="tlx-20251231.xsd#tlx_NumberOfLoanAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_tlx_NumberOfLoanAgreements_019b0124-055c-7092-a732-214729efa327" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NotionalAmount_019b0124-055c-7673-87d5-96ac92bf80de" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_ifrs-full_NotionalAmount_019b0124-055c-7673-87d5-96ac92bf80de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsMaturityTerm_019b0124-055c-77a2-ae3e-75d28aa35c9e" xlink:href="tlx-20251231.xsd#tlx_BorrowingsMaturityTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_tlx_BorrowingsMaturityTerm_019b0124-055c-77a2-ae3e-75d28aa35c9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsHolidayPeriodTerm_019b0124-055c-70c5-91ed-8ff7abc7dadf" xlink:href="tlx-20251231.xsd#tlx_BorrowingsHolidayPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_tlx_BorrowingsHolidayPeriodTerm_019b0124-055c-70c5-91ed-8ff7abc7dadf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UndrawnBorrowingFacilities_019b0124-055c-7357-9e1b-b62b95fb96a0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UndrawnBorrowingFacilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_ifrs-full_UndrawnBorrowingFacilities_019b0124-055c-7357-9e1b-b62b95fb96a0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BorrowingsCovenantPercentageOfCapitalAndReservesWhichCumulativeLossesShouldNotExceed_019b0124-055c-7bbf-a7b5-7a7f8aad697b" xlink:href="tlx-20251231.xsd#tlx_BorrowingsCovenantPercentageOfCapitalAndReservesWhichCumulativeLossesShouldNotExceed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7795-967c-d4959c61d668" xlink:to="loc_tlx_BorrowingsCovenantPercentageOfCapitalAndReservesWhichCumulativeLossesShouldNotExceed_019b0124-055c-7bbf-a7b5-7a7f8aad697b" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsWorkingCapitalFacilityDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsWorkingCapitalFacilityDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsWorkingCapitalFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7488-b019-250879adf6fe" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7960-b14d-1d9dbc1a0e8a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7488-b019-250879adf6fe" xlink:to="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7960-b14d-1d9dbc1a0e8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7061-94df-b8b55bebc5bb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b0124-055c-7960-b14d-1d9dbc1a0e8a" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7061-94df-b8b55bebc5bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7061-94df-b8b55bebc5bb_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7061-94df-b8b55bebc5bb" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7061-94df-b8b55bebc5bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7c61-a254-10c4b25f9071" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7061-94df-b8b55bebc5bb" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7c61-a254-10c4b25f9071" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_HSBCBankAustraliaLimitedMember_019b0124-055c-7e5a-b2ac-d3913762f20b" xlink:href="tlx-20251231.xsd#tlx_HSBCBankAustraliaLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7c61-a254-10c4b25f9071" xlink:to="loc_tlx_HSBCBankAustraliaLimitedMember_019b0124-055c-7e5a-b2ac-d3913762f20b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WorkingCapitalFacilityAbstract_019b0124-055c-73f5-addf-54a195aecea4" xlink:href="tlx-20251231.xsd#tlx_WorkingCapitalFacilityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b0124-055c-7488-b019-250879adf6fe" xlink:to="loc_tlx_WorkingCapitalFacilityAbstract_019b0124-055c-73f5-addf-54a195aecea4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DebtInstrumentMaximumBorrowingFacility_019b0124-055c-754e-a29a-344ec72bb3c7" xlink:href="tlx-20251231.xsd#tlx_DebtInstrumentMaximumBorrowingFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WorkingCapitalFacilityAbstract_019b0124-055c-73f5-addf-54a195aecea4" xlink:to="loc_tlx_DebtInstrumentMaximumBorrowingFacility_019b0124-055c-754e-a29a-344ec72bb3c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingCostsIncurred_019b0124-055c-7cc3-a1f3-9cd9cf234a26" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingCostsIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WorkingCapitalFacilityAbstract_019b0124-055c-73f5-addf-54a195aecea4" xlink:to="loc_ifrs-full_BorrowingCostsIncurred_019b0124-055c-7cc3-a1f3-9cd9cf234a26" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsConvertibleBondsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsConvertibleBondsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsConvertibleBondsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7e47-aeb0-b008a290f32d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:to="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7e47-aeb0-b008a290f32d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7f71-b55b-7aede9e4713c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7e47-aeb0-b008a290f32d" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7f71-b55b-7aede9e4713c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7f71-b55b-7aede9e4713c_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7f71-b55b-7aede9e4713c" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-7f71-b55b-7aede9e4713c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-76a8-87fb-a53a18eb6c8b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b0124-055c-7f71-b55b-7aede9e4713c" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-76a8-87fb-a53a18eb6c8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConvertibleBondsMember_019b0124-055c-7e7c-b3dc-6ca8ebcf6da0" xlink:href="tlx-20251231.xsd#tlx_ConvertibleBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b0124-055c-76a8-87fb-a53a18eb6c8b" xlink:to="loc_tlx_ConvertibleBondsMember_019b0124-055c-7e7c-b3dc-6ca8ebcf6da0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BondsIssued_019b0124-055c-7852-9ae2-5cd8f3a7c112" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BondsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:to="loc_ifrs-full_BondsIssued_019b0124-055c-7852-9ae2-5cd8f3a7c112" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConversionPrice_019b0124-055c-7d94-a1ab-807444044e0a" xlink:href="tlx-20251231.xsd#tlx_ConversionPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:to="loc_tlx_ConversionPrice_019b0124-055c-7d94-a1ab-807444044e0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProceedsFromIssueOfBondsNotesAndDebentures_019b0124-055c-7e0e-829e-995f62e3dbe7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProceedsFromIssueOfBondsNotesAndDebentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:to="loc_ifrs-full_ProceedsFromIssueOfBondsNotesAndDebentures_019b0124-055c-7e0e-829e-995f62e3dbe7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsInterestRate_019b0124-055c-70f9-bc42-59465cf18e55" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-7af0-a9e9-1bd6575ed6ec" xlink:to="loc_ifrs-full_BorrowingsInterestRate_019b0124-055c-70f9-bc42-59465cf18e55" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsScheduleofConvertibleBondsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsScheduleofConvertibleBondsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsScheduleofConvertibleBondsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b1f-ec0e-7518-87d4-9b59d62b6550" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b1f-ec0e-7518-87d4-9b59d62b6550" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b3b1f-ec0e-768b-b96f-65b3ec306bfb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b1f-ec0e-7518-87d4-9b59d62b6550" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b3b1f-ec0e-768b-b96f-65b3ec306bfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b3b1f-ec0e-768b-b96f-65b3ec306bfb_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b3b1f-ec0e-768b-b96f-65b3ec306bfb" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b3b1f-ec0e-768b-b96f-65b3ec306bfb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b3b1f-ec0e-79ad-afb9-418bf38c2251" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b3b1f-ec0e-768b-b96f-65b3ec306bfb" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b3b1f-ec0e-79ad-afb9-418bf38c2251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConvertibleBondsMember_019b3b1f-ec0e-7c0a-be21-7c082ea6f7dc" xlink:href="tlx-20251231.xsd#tlx_ConvertibleBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b3b1f-ec0e-79ad-afb9-418bf38c2251" xlink:to="loc_tlx_ConvertibleBondsMember_019b3b1f-ec0e-7c0a-be21-7c082ea6f7dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019c67bf-65ae-70d6-b135-e49648ed7a78" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_Borrowings_019c67bf-65ae-70d6-b135-e49648ed7a78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NotionalAmount_019b3b1f-ec0e-71b5-b959-dc26bf02c6c7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_NotionalAmount_019b3b1f-ec0e-71b5-b959-dc26bf02c6c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingCostsIncurred_019b3b1f-ec0e-7cf1-9838-8e93cc02c9d5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingCostsIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_BorrowingCostsIncurred_019b3b1f-ec0e-7cf1-9838-8e93cc02c9d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherEquitySecuritiesValueOfConversionRights_019b3b1f-ec0e-7935-a24f-809ef77a86ab" xlink:href="tlx-20251231.xsd#tlx_OtherEquitySecuritiesValueOfConversionRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_tlx_OtherEquitySecuritiesValueOfConversionRights_019b3b1f-ec0e-7935-a24f-809ef77a86ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UnwindOfDiscount_019b3b1f-ec0e-7998-9f58-1a7e8fa59497" xlink:href="tlx-20251231.xsd#tlx_UnwindOfDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_tlx_UnwindOfDiscount_019b3b1f-ec0e-7998-9f58-1a7e8fa59497" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_InterestExpenseOnBonds_019b3b1f-ec0e-7fd1-a2bf-315f389fa39a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InterestExpenseOnBonds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_InterestExpenseOnBonds_019b3b1f-ec0e-7fd1-a2bf-315f389fa39a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_InterestPaidOnConvertibleBonds_019b3b1f-ec0e-7b74-8191-cfd43aa322e5" xlink:href="tlx-20251231.xsd#tlx_InterestPaidOnConvertibleBonds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_tlx_InterestPaidOnConvertibleBonds_019b3b1f-ec0e-7b74-8191-cfd43aa322e5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInForeignExchangeDifferencesInConvertibleBonds_019c12cc-fa2d-79e0-bd25-01783ab4e9c7" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInForeignExchangeDifferencesInConvertibleBonds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_tlx_IncreaseDecreaseInForeignExchangeDifferencesInConvertibleBonds_019c12cc-fa2d-79e0-bd25-01783ab4e9c7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019c67bf-9b78-707d-851a-55f417f1af57" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ShorttermBorrowings_019b3b1f-ec0e-7c9e-aabf-1b6ffef0e683" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShorttermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_ShorttermBorrowings_019b3b1f-ec0e-7c9e-aabf-1b6ffef0e683" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LongtermBorrowings_019b3b1f-ec0e-7bfb-ac7e-8b53ed2eb0b9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LongtermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b1f-ec0e-71fc-b912-7b49f45fe427" xlink:to="loc_ifrs-full_LongtermBorrowings_019b3b1f-ec0e-7bfb-ac7e-8b53ed2eb0b9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019b3b1f-ec0e-7642-b477-f6ed653cd1fa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsReconciliationofLiabilitiesArisingfromFinancingActivitiesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsReconciliationofLiabilitiesArisingfromFinancingActivitiesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsReconciliationofLiabilitiesArisingfromFinancingActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-79ad-bbbe-99acf2577bb7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7737-835a-94b81611924e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-79ad-bbbe-99acf2577bb7" xlink:to="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7737-835a-94b81611924e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesAxis_019b0124-055c-752f-9b78-a77f50264ef0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable_019b0124-055c-7737-835a-94b81611924e" xlink:to="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesAxis_019b0124-055c-752f-9b78-a77f50264ef0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-752f-9b78-a77f50264ef0_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesAxis_019b0124-055c-752f-9b78-a77f50264ef0" xlink:to="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-752f-9b78-a77f50264ef0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesAxis_019b0124-055c-752f-9b78-a77f50264ef0" xlink:to="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BankLoansMember_019b0124-055c-7624-9f4d-1080348204c5" xlink:href="tlx-20251231.xsd#tlx_BankLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:to="loc_tlx_BankLoansMember_019b0124-055c-7624-9f4d-1080348204c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WorkingCapitalFacilityMember_019c3057-8770-73d1-bf0e-73bdd940f7fa" xlink:href="tlx-20251231.xsd#tlx_WorkingCapitalFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:to="loc_tlx_WorkingCapitalFacilityMember_019c3057-8770-73d1-bf0e-73bdd940f7fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConvertibleBondsMember_019b0124-055c-784f-8407-d654486f4c07" xlink:href="tlx-20251231.xsd#tlx_ConvertibleBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:to="loc_tlx_ConvertibleBondsMember_019b0124-055c-784f-8407-d654486f4c07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-055c-7e6d-8fdb-9593d8431ed5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesArisingFromFinancingActivitiesDomain_019b0124-055c-7a9c-9b93-5d2359b66774" xlink:to="loc_ifrs-full_LeaseLiabilitiesMember_019b0124-055c-7e6d-8fdb-9593d8431ed5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract_019b0124-055c-7c88-85d8-48365c13dc17" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems_019b0124-055c-79ad-bbbe-99acf2577bb7" xlink:to="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract_019b0124-055c-7c88-85d8-48365c13dc17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesArisingFromFinancingActivities_019b0124-055c-7664-b78d-624686c61e07" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract_019b0124-055c-7c88-85d8-48365c13dc17" xlink:to="loc_ifrs-full_LiabilitiesArisingFromFinancingActivities_019b0124-055c-7664-b78d-624686c61e07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughFinancingCashFlowsLiabilitiesArisingFromFinancingActivities_019b0124-055c-7a10-b7d1-a80f3ac48763" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughFinancingCashFlowsLiabilitiesArisingFromFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract_019b0124-055c-7c88-85d8-48365c13dc17" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughFinancingCashFlowsLiabilitiesArisingFromFinancingActivities_019b0124-055c-7a10-b7d1-a80f3ac48763" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughOtherChangesLiabilitiesArisingFromFinancingActivities_019b0124-055c-786a-aab0-e51b2bbccde0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughOtherChangesLiabilitiesArisingFromFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesAbstract_019b0124-055c-7c88-85d8-48365c13dc17" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughOtherChangesLiabilitiesArisingFromFinancingActivities_019b0124-055c-786a-aab0-e51b2bbccde0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesArisingFromFinancingActivities_019b0124-055c-7ea7-ad4c-e46cb9a6fda6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivities"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/BorrowingsScheduleofConvertibleBondsCarryingAmountandFairValueDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#BorrowingsScheduleofConvertibleBondsCarryingAmountandFairValueDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/BorrowingsScheduleofConvertibleBondsCarryingAmountandFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b36-e07b-7cbc-9761-f47096a9b913" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b36-e07b-7b2e-8236-e507901ba048" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b36-e07b-7cbc-9761-f47096a9b913" xlink:to="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b36-e07b-7b2e-8236-e507901ba048" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameAxis_019b3b36-e07b-7042-9fe8-cebbd527d3c2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable_019b3b36-e07b-7b2e-8236-e507901ba048" xlink:to="loc_ifrs-full_BorrowingsByNameAxis_019b3b36-e07b-7042-9fe8-cebbd527d3c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7042-9fe8-cebbd527d3c2_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b3b36-e07b-7042-9fe8-cebbd527d3c2" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7042-9fe8-cebbd527d3c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7db7-ab11-f9b9522aeed1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BorrowingsByNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BorrowingsByNameAxis_019b3b36-e07b-7042-9fe8-cebbd527d3c2" xlink:to="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7db7-ab11-f9b9522aeed1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BankLoansMember_019b3b36-e07b-769a-95ab-9894508e712e" xlink:href="tlx-20251231.xsd#tlx_BankLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7db7-ab11-f9b9522aeed1" xlink:to="loc_tlx_BankLoansMember_019b3b36-e07b-769a-95ab-9894508e712e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConvertibleBondsMember_019b3b36-e07b-7e4e-a3a2-945f827b0a2e" xlink:href="tlx-20251231.xsd#tlx_ConvertibleBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BorrowingsByNameDomain_019b3b36-e07b-7db7-ab11-f9b9522aeed1" xlink:to="loc_tlx_ConvertibleBondsMember_019b3b36-e07b-7e4e-a3a2-945f827b0a2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019b3b36-e07b-779e-90d6-bbff09f5d33a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b36-e07b-7cbc-9761-f47096a9b913" xlink:to="loc_ifrs-full_Borrowings_019b3b36-e07b-779e-90d6-bbff09f5d33a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialLiabilitiesAtFairValue_019b3b36-e07b-7537-867f-f84188b101c2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems_019b3b36-e07b-7cbc-9761-f47096a9b913" xlink:to="loc_ifrs-full_FinancialLiabilitiesAtFairValue_019b3b36-e07b-7537-867f-f84188b101c2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ContractliabilitiesGrandpharmastrategicpartnershipDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ContractliabilitiesGrandpharmastrategicpartnershipDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ContractliabilitiesGrandpharmastrategicpartnershipDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-055c-74a4-b2a0-ece30c0582eb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-055c-7ee3-aa94-aa864a08086b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-055c-74a4-b2a0-ece30c0582eb" xlink:to="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-055c-7ee3-aa94-aa864a08086b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfContractsAxis_019b0124-055c-7087-8065-da8cd7ec645f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfContractsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable_019b0124-055c-7ee3-aa94-aa864a08086b" xlink:to="loc_ifrs-full_TypesOfContractsAxis_019b0124-055c-7087-8065-da8cd7ec645f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfContractsDomain_019b0124-055c-7087-8065-da8cd7ec645f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfContractsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfContractsAxis_019b0124-055c-7087-8065-da8cd7ec645f" xlink:to="loc_ifrs-full_TypesOfContractsDomain_019b0124-055c-7087-8065-da8cd7ec645f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfContractsDomain_019b0124-055c-74ee-9e32-d24694a9e4e4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfContractsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfContractsAxis_019b0124-055c-7087-8065-da8cd7ec645f" xlink:to="loc_ifrs-full_TypesOfContractsDomain_019b0124-055c-74ee-9e32-d24694a9e4e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrandPharmaceuticalGroupLimitedMember_019b0124-055c-7130-a2eb-bcb63ce5c2ec" xlink:href="tlx-20251231.xsd#tlx_GrandPharmaceuticalGroupLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfContractsDomain_019b0124-055c-74ee-9e32-d24694a9e4e4" xlink:to="loc_tlx_GrandPharmaceuticalGroupLimitedMember_019b0124-055c-7130-a2eb-bcb63ce5c2ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrandPharmaStrategicPartnershipAbstract_019b0124-055c-7bb8-a2ef-a274bebd1725" xlink:href="tlx-20251231.xsd#tlx_GrandPharmaStrategicPartnershipAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems_019b0124-055c-74a4-b2a0-ece30c0582eb" xlink:to="loc_tlx_GrandPharmaStrategicPartnershipAbstract_019b0124-055c-7bb8-a2ef-a274bebd1725" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NonRefundableUpfrontPaymentReceived_019b0124-055c-7200-aa5c-536c2ad78d8a" xlink:href="tlx-20251231.xsd#tlx_NonRefundableUpfrontPaymentReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_GrandPharmaStrategicPartnershipAbstract_019b0124-055c-7bb8-a2ef-a274bebd1725" xlink:to="loc_tlx_NonRefundableUpfrontPaymentReceived_019b0124-055c-7200-aa5c-536c2ad78d8a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/LeaseliabilitiesScheduleofInterestexpenserelatingtoleasesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#LeaseliabilitiesScheduleofInterestexpenserelatingtoleasesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/LeaseliabilitiesScheduleofInterestexpenserelatingtoleasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-055c-7277-b4ff-c5faa2458daa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-055c-70df-9e25-a9a6871bf184" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-055c-7277-b4ff-c5faa2458daa" xlink:to="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-055c-70df-9e25-a9a6871bf184" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-055c-734f-8ed8-3288c1ba80df" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable_019b0124-055c-70df-9e25-a9a6871bf184" xlink:to="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-055c-734f-8ed8-3288c1ba80df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-734f-8ed8-3288c1ba80df_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-055c-734f-8ed8-3288c1ba80df" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-734f-8ed8-3288c1ba80df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-79a0-a2c0-62d902e94d42" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfAssetsAxis_019b0124-055c-734f-8ed8-3288c1ba80df" xlink:to="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-79a0-a2c0-62d902e94d42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LandAndBuildingsMember_019b0124-055c-71f3-a2cd-182998eb9210" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LandAndBuildingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-79a0-a2c0-62d902e94d42" xlink:to="loc_ifrs-full_LandAndBuildingsMember_019b0124-055c-71f3-a2cd-182998eb9210" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MotorVehiclesMember_019b0124-055c-70e0-a831-486a6274b8e5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MotorVehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfAssetsDomain_019b0124-055c-79a0-a2c0-62d902e94d42" xlink:to="loc_ifrs-full_MotorVehiclesMember_019b0124-055c-70e0-a831-486a6274b8e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_InterestExpenseOnLeaseLiabilities_019b0124-055c-7418-8c7c-fc3e20fe768c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InterestExpenseOnLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsLineItems_019b0124-055c-7277-b4ff-c5faa2458daa" xlink:to="loc_ifrs-full_InterestExpenseOnLeaseLiabilities_019b0124-055c-7418-8c7c-fc3e20fe768c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ProvisionsScheduleofProvisionsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ProvisionsScheduleofProvisionsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ProvisionsScheduleofProvisionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b0124-055c-739d-95d4-92eda22c2059" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOtherProvisionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b0124-055c-76ce-af39-fa29773144eb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOtherProvisionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b0124-055c-739d-95d4-92eda22c2059" xlink:to="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b0124-055c-76ce-af39-fa29773144eb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfProvisionsAxis_019b0124-055c-7153-8a8f-24ffce2f08f9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfProvisionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b0124-055c-76ce-af39-fa29773144eb" xlink:to="loc_ifrs-full_ClassesOfProvisionsAxis_019b0124-055c-7153-8a8f-24ffce2f08f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7153-8a8f-24ffce2f08f9_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfOtherProvisionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfProvisionsAxis_019b0124-055c-7153-8a8f-24ffce2f08f9" xlink:to="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7153-8a8f-24ffce2f08f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7b3b-a844-9456dc9bba79" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfOtherProvisionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfProvisionsAxis_019b0124-055c-7153-8a8f-24ffce2f08f9" xlink:to="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7b3b-a844-9456dc9bba79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GovernmentGrantLiabilityMember_019b0124-055c-79b9-bf4c-c77b62a3faa3" xlink:href="tlx-20251231.xsd#tlx_GovernmentGrantLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7b3b-a844-9456dc9bba79" xlink:to="loc_tlx_GovernmentGrantLiabilityMember_019b0124-055c-79b9-bf4c-c77b62a3faa3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember_019b0124-055c-74ca-911f-35c2441857c2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019b0124-055c-7b3b-a844-9456dc9bba79" xlink:to="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember_019b0124-055c-74ca-911f-35c2441857c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b0124-055c-739d-95d4-92eda22c2059" xlink:to="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Provisions_019b0124-055c-7280-b69c-f53d4b193c2e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Provisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_Provisions_019b0124-055c-7280-b69c-f53d4b193c2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughRemeasurementOtherProvisions_019c75e7-cc29-7eee-bc32-fd76b642468a" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughRemeasurementOtherProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_tlx_IncreaseDecreaseThroughRemeasurementOtherProvisions_019c75e7-cc29-7eee-bc32-fd76b642468a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughTimeValueOfMoneyAdjustmentOtherProvisions_019b0124-055c-7b2c-9a0a-be102e76950f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughTimeValueOfMoneyAdjustmentOtherProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughTimeValueOfMoneyAdjustmentOtherProvisions_019b0124-055c-7b2c-9a0a-be102e76950f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherProvisionsChargedToProfitLoss_019b0124-055c-7e42-a2ae-a44fb467096f" xlink:href="tlx-20251231.xsd#tlx_OtherProvisionsChargedToProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_tlx_OtherProvisionsChargedToProfitLoss_019b0124-055c-7e42-a2ae-a44fb467096f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesOtherProvisions_019b0124-055c-7ba8-83b3-5b2b8f4dcfea" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesOtherProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesOtherProvisions_019b0124-055c-7ba8-83b3-5b2b8f4dcfea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInOtherProvisionAdjustedToPropertyPlantAndEquipment_019b0124-055c-7938-9fc4-a9d256039de3" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInOtherProvisionAdjustedToPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_tlx_IncreaseDecreaseInOtherProvisionAdjustedToPropertyPlantAndEquipment_019b0124-055c-7938-9fc4-a9d256039de3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProvisionUsedOtherProvisions_019b0124-055c-7be0-84a5-f368470f2100" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProvisionUsedOtherProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_ProvisionUsedOtherProvisions_019b0124-055c-7be0-84a5-f368470f2100" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Provisions_019b0124-055c-71e4-ac2a-57ec0d784af5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Provisions"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentProvisions_019b0124-055c-79f5-a2e1-ac4bf36f7c5a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_CurrentProvisions_019b0124-055c-79f5-a2e1-ac4bf36f7c5a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentProvisions_019b0124-055c-722d-877e-a1767e5ce2c2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ReconciliationOfChangesInOtherProvisionsAbstract_019b0124-055c-71b3-a1b3-cdfb4178ddff" xlink:to="loc_ifrs-full_NoncurrentProvisions_019b0124-055c-722d-877e-a1767e5ce2c2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Provisions_019b0124-055c-7851-932a-f7dc56b3ff85" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Provisions"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ProvisionsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ProvisionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ProvisionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b3b56-2302-7c9c-ba40-c0be0356f205" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOtherProvisionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b3b56-2302-73f3-b056-9f529984d34d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfOtherProvisionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b3b56-2302-7c9c-ba40-c0be0356f205" xlink:to="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b3b56-2302-73f3-b056-9f529984d34d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfProvisionsAxis_019be985-c7a9-7288-af89-874148fb19b7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfProvisionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsTable_019b3b56-2302-73f3-b056-9f529984d34d" xlink:to="loc_ifrs-full_ClassesOfProvisionsAxis_019be985-c7a9-7288-af89-874148fb19b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7288-af89-874148fb19b7_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfOtherProvisionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfProvisionsAxis_019be985-c7a9-7288-af89-874148fb19b7" xlink:to="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7288-af89-874148fb19b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7d68-9d50-6638bf6c117e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfOtherProvisionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfProvisionsAxis_019be985-c7a9-7288-af89-874148fb19b7" xlink:to="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7d68-9d50-6638bf6c117e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GovernmentGrantLiabilityMember_019be986-25e6-71be-b7b0-bc9407e13564" xlink:href="tlx-20251231.xsd#tlx_GovernmentGrantLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7d68-9d50-6638bf6c117e" xlink:to="loc_tlx_GovernmentGrantLiabilityMember_019be986-25e6-71be-b7b0-bc9407e13564" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember_019be987-4a9a-7726-8362-68b74ecb9c55" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfOtherProvisionsDomain_019be985-c7a9-7d68-9d50-6638bf6c117e" xlink:to="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember_019be987-4a9a-7726-8362-68b74ecb9c55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections_019b3b56-2302-7977-972f-318250e278d5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b3b56-2302-7c9c-ba40-c0be0356f205" xlink:to="loc_ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections_019b3b56-2302-7977-972f-318250e278d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NewProvisionsOtherProvisions_019b3b56-a7d1-74a0-b84a-d85403f858e6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NewProvisionsOtherProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b3b56-2302-7c9c-ba40-c0be0356f205" xlink:to="loc_ifrs-full_NewProvisionsOtherProvisions_019b3b56-a7d1-74a0-b84a-d85403f858e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DecommissioningCostsExpectedToBeIncurred_019b3b56-a7d1-7bea-958b-f754882a15f4" xlink:href="tlx-20251231.xsd#tlx_DecommissioningCostsExpectedToBeIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfOtherProvisionsLineItems_019b3b56-2302-7c9c-ba40-c0be0356f205" xlink:to="loc_tlx_DecommissioningCostsExpectedToBeIncurred_019b3b56-a7d1-7bea-958b-f754882a15f4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ContingentconsiderationNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ContingentconsiderationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ContingentconsiderationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:href="tlx-20251231.xsd#tlx_DetailedInformationAboutContingentConsiderationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b0124-055c-7a59-93c8-68c1f24f3921" xlink:href="tlx-20251231.xsd#tlx_DetailedInformationAboutContingentConsiderationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b0124-055c-7a59-93c8-68c1f24f3921" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b53-b4be-65d05035611e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b0124-055c-7a59-93c8-68c1f24f3921" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b53-b4be-65d05035611e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7b53-b4be-65d05035611e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b53-b4be-65d05035611e" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7b53-b4be-65d05035611e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b53-b4be-65d05035611e" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ANMIMember_019b0124-055c-7d24-a8ec-e90eef8ebb2f" xlink:href="tlx-20251231.xsd#tlx_ANMIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:to="loc_tlx_ANMIMember_019b0124-055c-7d24-a8ec-e90eef8ebb2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TheraPharmMember_019b0124-055c-7df9-aeda-15ee14682d96" xlink:href="tlx-20251231.xsd#tlx_TheraPharmMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:to="loc_tlx_TheraPharmMember_019b0124-055c-7df9-aeda-15ee14682d96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IsoTherapeuticsGroupLLCMember_019bfd45-41ed-7c29-98f4-f0bed8b47094" xlink:href="tlx-20251231.xsd#tlx_IsoTherapeuticsGroupLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:to="loc_tlx_IsoTherapeuticsGroupLLCMember_019bfd45-41ed-7c29-98f4-f0bed8b47094" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSMember_019bfd45-41ed-72c1-b257-db7e1c46b37c" xlink:href="tlx-20251231.xsd#tlx_ARTMSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7e14-bcdd-c0e297b370e5" xlink:to="loc_tlx_ARTMSMember_019bfd45-41ed-72c1-b257-db7e1c46b37c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FutureVariablePayments_019b0124-055c-7b36-8c0d-a982b59c135d" xlink:href="tlx-20251231.xsd#tlx_FutureVariablePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_FutureVariablePayments_019b0124-055c-7b36-8c0d-a982b59c135d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GainsLossesFromRemeasurementOfContingentConsideration_019c44cf-32aa-72f6-96b0-42cdbbae3868" xlink:href="tlx-20251231.xsd#tlx_GainsLossesFromRemeasurementOfContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_GainsLossesFromRemeasurementOfContingentConsideration_019c44cf-32aa-72f6-96b0-42cdbbae3868" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentConsiderationCovenantSalesVolumesAndOutstandingBalanceSettled_019c44d3-edcc-79a8-8d04-b037302c7064" xlink:href="tlx-20251231.xsd#tlx_ContingentConsiderationCovenantSalesVolumesAndOutstandingBalanceSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_ContingentConsiderationCovenantSalesVolumesAndOutstandingBalanceSettled_019c44d3-edcc-79a8-8d04-b037302c7064" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MilestonePaymentOnCompletionOfPhaseIIIPivotalRegistrationTrial_019b0124-055c-7ed8-9282-808f4d574d76" xlink:href="tlx-20251231.xsd#tlx_MilestonePaymentOnCompletionOfPhaseIIIPivotalRegistrationTrial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_MilestonePaymentOnCompletionOfPhaseIIIPivotalRegistrationTrial_019b0124-055c-7ed8-9282-808f4d574d76" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MilestonePaymentOnReceiptOfSecondMarketingApproval_019b0124-055c-769a-8673-c708ba510113" xlink:href="tlx-20251231.xsd#tlx_MilestonePaymentOnReceiptOfSecondMarketingApproval"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_MilestonePaymentOnReceiptOfSecondMarketingApproval_019b0124-055c-769a-8673-c708ba510113" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentConsiderationCovenantPercentageOfNetSales_019b0124-055c-7626-8e8c-787d96488b68" xlink:href="tlx-20251231.xsd#tlx_ContingentConsiderationCovenantPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_ContingentConsiderationCovenantPercentageOfNetSales_019b0124-055c-7626-8e8c-787d96488b68" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections_019b0124-055c-7c5c-a1f6-a0a362da58e4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections_019b0124-055c-7c5c-a1f6-a0a362da58e4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019bfd45-41ed-7046-969f-f5e34160f5bf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_ifrs-full_ContingentConsiderationRecognisedAsOfAcquisitionDate_019bfd45-41ed-7046-969f-f5e34160f5bf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EarnOutPaymentsTerminationPeriod_019bfd45-41ed-7aa8-941f-76fc940097bf" xlink:href="tlx-20251231.xsd#tlx_EarnOutPaymentsTerminationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b0124-055c-7747-b5fc-7157d851d27b" xlink:to="loc_tlx_EarnOutPaymentsTerminationPeriod_019bfd45-41ed-7aa8-941f-76fc940097bf" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ContingentconsiderationScheduleofContingentConsiderationValuationDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ContingentconsiderationScheduleofContingentConsiderationValuationDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ContingentconsiderationScheduleofContingentConsiderationValuationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:href="tlx-20251231.xsd#tlx_DetailedInformationAboutContingentConsiderationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b3b70-ef2e-7215-b48f-755bc674a86b" xlink:href="tlx-20251231.xsd#tlx_DetailedInformationAboutContingentConsiderationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:to="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b3b70-ef2e-7215-b48f-755bc674a86b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b3b70-ef2e-7215-b48f-755bc674a86b" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7eb4-acfa-ff1bcf1cdc5e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b3b70-ef2e-7ff4-a61e-b9f7da95d1d1" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7eb4-acfa-ff1bcf1cdc5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TheraPharmMember_019b3b70-ef2e-7a12-8ede-147a065e72a8" xlink:href="tlx-20251231.xsd#tlx_TheraPharmMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7eb4-acfa-ff1bcf1cdc5e" xlink:to="loc_tlx_TheraPharmMember_019b3b70-ef2e-7a12-8ede-147a065e72a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSMember_019be994-6dec-73d6-9bb2-292feec677ec" xlink:href="tlx-20251231.xsd#tlx_ARTMSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b3b70-ef2e-7eb4-acfa-ff1bcf1cdc5e" xlink:to="loc_tlx_ARTMSMember_019be994-6dec-73d6-9bb2-292feec677ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnobservableInputsAxis_019b3b70-ef2e-76e9-92f0-24b414ff2c00" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnobservableInputsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationTable_019b3b70-ef2e-7215-b48f-755bc674a86b" xlink:to="loc_ifrs-full_UnobservableInputsAxis_019b3b70-ef2e-76e9-92f0-24b414ff2c00" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-76e9-92f0-24b414ff2c00_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnobservableInputsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_UnobservableInputsAxis_019b3b70-ef2e-76e9-92f0-24b414ff2c00" xlink:to="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-76e9-92f0-24b414ff2c00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_UnobservableInputsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_UnobservableInputsAxis_019b3b70-ef2e-76e9-92f0-24b414ff2c00" xlink:to="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DiscountRateMeasurementInputMember_019b3b70-ef2e-7907-bb81-18f1d9f00000" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DiscountRateMeasurementInputMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:to="loc_ifrs-full_DiscountRateMeasurementInputMember_019b3b70-ef2e-7907-bb81-18f1d9f00000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ExpectedSalesVolumeMember_019b3b70-ef2e-7b37-aa0a-7c7e84d0a39d" xlink:href="tlx-20251231.xsd#tlx_ExpectedSalesVolumeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:to="loc_tlx_ExpectedSalesVolumeMember_019b3b70-ef2e-7b37-aa0a-7c7e84d0a39d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NetSalesPricePerUnitMember_019b3b70-ef2e-797b-b887-494e9cf2a0fe" xlink:href="tlx-20251231.xsd#tlx_NetSalesPricePerUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:to="loc_tlx_NetSalesPricePerUnitMember_019b3b70-ef2e-797b-b887-494e9cf2a0fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ApprovalForMarketingAuthorizationProbabilitySuccessFactorMember_019b3b70-ef2e-70fb-a281-5e05dd4b9f99" xlink:href="tlx-20251231.xsd#tlx_ApprovalForMarketingAuthorizationProbabilitySuccessFactorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:to="loc_tlx_ApprovalForMarketingAuthorizationProbabilitySuccessFactorMember_019b3b70-ef2e-70fb-a281-5e05dd4b9f99" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MilestoneAchievementProbabilityOfSuccessFactorMember_019be98e-1a1a-75da-9d1c-5795cc5dce5f" xlink:href="tlx-20251231.xsd#tlx_MilestoneAchievementProbabilityOfSuccessFactorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_UnobservableInputsDomain_019b3b70-ef2e-7ac3-970e-a453fb65cff9" xlink:to="loc_tlx_MilestoneAchievementProbabilityOfSuccessFactorMember_019be98e-1a1a-75da-9d1c-5795cc5dce5f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities_019c54d1-c9e5-743d-9e25-b114cb0178fa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities_019c54d1-c9e5-743d-9e25-b114cb0178fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities_019c54d1-fec4-72db-a0ec-fa0ea6f68619" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities_019c54d1-fec4-72db-a0ec-fa0ea6f68619" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputLiabilities_019b3b70-ef2e-7acb-a464-65f1407c643b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputLiabilities_019b3b70-ef2e-7acb-a464-65f1407c643b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputLiabilities_019b3b70-ef2e-79b4-b826-664156c3093d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_DetailedInformationAboutContingentConsiderationLineItems_019b3b70-ef2e-7347-a087-5af69d58d243" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputLiabilities_019b3b70-ef2e-79b4-b826-664156c3093d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquityShareCapitalDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquityShareCapitalDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquityShareCapitalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055c-7ab6-9e61-befa1e0c7855" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055c-7ab6-9e61-befa1e0c7855" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055c-794d-b233-926a54bfb4c1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055c-7ab6-9e61-befa1e0c7855" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055c-794d-b233-926a54bfb4c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055c-794d-b233-926a54bfb4c1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055c-794d-b233-926a54bfb4c1" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055c-794d-b233-926a54bfb4c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055c-7e0a-9636-71181da5244b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055c-794d-b233-926a54bfb4c1" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055c-7e0a-9636-71181da5244b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapitalMember_019b0124-055c-7e28-87ae-1b1756946d52" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055c-7e0a-9636-71181da5244b" xlink:to="loc_ifrs-full_IssuedCapitalMember_019b0124-055c-7e28-87ae-1b1756946d52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b03-9e6c-e3b485121991" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055c-7ab6-9e61-befa1e0c7855" xlink:to="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b03-9e6c-e3b485121991" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7b03-9e6c-e3b485121991_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b03-9e6c-e3b485121991" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7b03-9e6c-e3b485121991_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BusinessCombinationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_BusinessCombinationsAxis_019b0124-055c-7b03-9e6c-e3b485121991" xlink:to="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_DedicaidGmbHMember_019b0124-055c-718f-ac1b-a885d7cf213f" xlink:href="tlx-20251231.xsd#tlx_DedicaidGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_DedicaidGmbHMember_019b0124-055c-718f-ac1b-a885d7cf213f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LightpointMedicalMember_019b0124-055c-74aa-979a-317db0aa99a2" xlink:href="tlx-20251231.xsd#tlx_LightpointMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_LightpointMedicalMember_019b0124-055c-74aa-979a-317db0aa99a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IsoTherapeuticsGroupLLCMember_019b0124-055c-794a-910a-61c14fcccfce" xlink:href="tlx-20251231.xsd#tlx_IsoTherapeuticsGroupLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_IsoTherapeuticsGroupLLCMember_019b0124-055c-794a-910a-61c14fcccfce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSIncMember_019b0124-055c-74a3-acee-4f1d75983ca8" xlink:href="tlx-20251231.xsd#tlx_ARTMSIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_ARTMSIncMember_019b0124-055c-74a3-acee-4f1d75983ca8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_QSAMBiosciencesIncMember_019b0124-055c-71bb-bdbf-ce4b43dd801b" xlink:href="tlx-20251231.xsd#tlx_QSAMBiosciencesIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_QSAMBiosciencesIncMember_019b0124-055c-71bb-bdbf-ce4b43dd801b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ImaginAbIncMember_019c12ce-5197-7a90-b922-98405bfb648d" xlink:href="tlx-20251231.xsd#tlx_ImaginAbIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_BusinessCombinationsDomain_019b0124-055c-7550-a08f-e59625d90865" xlink:to="loc_tlx_ImaginAbIncMember_019c12ce-5197-7a90-b922-98405bfb648d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheAxis_019be695-e384-76f7-a178-85240e024287" xlink:href="tlx-20251231.xsd#tlx_TrancheAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055c-7ab6-9e61-befa1e0c7855" xlink:to="loc_tlx_TrancheAxis_019be695-e384-76f7-a178-85240e024287" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019be695-e384-76f7-a178-85240e024287_default" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_TrancheAxis_019be695-e384-76f7-a178-85240e024287" xlink:to="loc_tlx_TrancheDomain_019be695-e384-76f7-a178-85240e024287_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019be695-e384-7aff-9a69-85e119129706" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_TrancheAxis_019be695-e384-76f7-a178-85240e024287" xlink:to="loc_tlx_TrancheDomain_019be695-e384-7aff-9a69-85e119129706" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FirstTrancheMember_019be696-4de8-76bf-b51c-08db06e57307" xlink:href="tlx-20251231.xsd#tlx_FirstTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019be695-e384-7aff-9a69-85e119129706" xlink:to="loc_tlx_FirstTrancheMember_019be696-4de8-76bf-b51c-08db06e57307" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SecondTrancheMember_019be697-1fb7-73dc-8829-0f3c000b9182" xlink:href="tlx-20251231.xsd#tlx_SecondTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019be695-e384-7aff-9a69-85e119129706" xlink:to="loc_tlx_SecondTrancheMember_019be697-1fb7-73dc-8829-0f3c000b9182" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalAbstract_019b0124-055c-7584-98eb-a0bf4b3c7335" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalAbstract_019b0124-055c-7584-98eb-a0bf4b3c7335" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:href="tlx-20251231.xsd#tlx_NumberOfSharesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalAbstract_019b0124-055c-7584-98eb-a0bf4b3c7335" xlink:to="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055c-7fd7-a21a-4bd1f46d58ef" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:to="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055c-7fd7-a21a-4bd1f46d58ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseSharesIssuedThroughExerciseOfShareOptionsAndWarrants_019b0124-055d-763c-bbb3-b5db4b95ea64" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseSharesIssuedThroughExerciseOfShareOptionsAndWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:to="loc_tlx_IncreaseDecreaseSharesIssuedThroughExerciseOfShareOptionsAndWarrants_019b0124-055d-763c-bbb3-b5db4b95ea64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInNumberOfSharesIssued_019b0124-055d-7931-acec-8761ee82e596" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:to="loc_tlx_IncreaseDecreaseInNumberOfSharesIssued_019b0124-055d-7931-acec-8761ee82e596" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssued_019b0124-055d-7409-96a0-481b85e3f550" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfSharesAbstract_019bc515-3c87-7da4-b2e6-0baa28d02634" xlink:to="loc_tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssued_019b0124-055d-7409-96a0-481b85e3f550" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-7bf0-8ec9-ea7d338064dd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:href="tlx-20251231.xsd#tlx_ValueOfShareholdingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalAbstract_019b0124-055c-7584-98eb-a0bf4b3c7335" xlink:to="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapital_019b0124-055c-790c-a86e-c29be769459e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:to="loc_ifrs-full_IssuedCapital_019b0124-055c-790c-a86e-c29be769459e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SharesIssuedThroughExerciseOfShareOptionsAndWarrants_019b0124-055d-7028-82e6-d7851132b8fc" xlink:href="tlx-20251231.xsd#tlx_SharesIssuedThroughExerciseOfShareOptionsAndWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:to="loc_tlx_SharesIssuedThroughExerciseOfShareOptionsAndWarrants_019b0124-055d-7028-82e6-d7851132b8fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssueOfEquity_019b0124-055d-7a33-93ee-395539ec9ed7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssueOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:to="loc_ifrs-full_IssueOfEquity_019b0124-055d-7a33-93ee-395539ec9ed7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssues_019b0124-055d-7a3b-8dcd-83cb12f27299" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019bc515-d709-7277-82cc-7c13326aef6c" xlink:to="loc_tlx_IncreaseDecreaseInTransactionCostsArisingOnNewShareIssues_019b0124-055d-7a3b-8dcd-83cb12f27299" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapital_019b0124-055d-7e1b-b09d-136348ea52d4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapital"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_VolumeWeightedAveragePeriod_019b0124-055d-777e-9024-ed8f11ed2af1" xlink:href="tlx-20251231.xsd#tlx_VolumeWeightedAveragePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:to="loc_tlx_VolumeWeightedAveragePeriod_019b0124-055d-777e-9024-ed8f11ed2af1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_VolumeWeightedAveragePriceOfEquityInstruments_019b0124-055d-79c6-ac53-6f4fe9a58177" xlink:href="tlx-20251231.xsd#tlx_VolumeWeightedAveragePriceOfEquityInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:to="loc_tlx_VolumeWeightedAveragePriceOfEquityInstruments_019b0124-055d-79c6-ac53-6f4fe9a58177" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ParValuePerShare_019b0124-055d-72f5-a001-1d107384b577" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ParValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055c-78ca-bb71-9cf37b0ea587" xlink:to="loc_ifrs-full_ParValuePerShare_019b0124-055d-72f5-a001-1d107384b577" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquityNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019be683-5f6e-79d9-be40-17e3cb60790f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019be683-5f6e-701c-b51a-362fb71e13ed" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019be683-5f6e-79d9-be40-17e3cb60790f" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019be683-5f6e-701c-b51a-362fb71e13ed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfShareCapitalAxis_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfShareCapitalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019be683-5f6e-701c-b51a-362fb71e13ed" xlink:to="loc_ifrs-full_ClassesOfShareCapitalAxis_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfShareCapitalDomain_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfShareCapitalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfShareCapitalAxis_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2" xlink:to="loc_ifrs-full_ClassesOfShareCapitalDomain_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfShareCapitalDomain_019be683-5f6e-7bab-91f1-6a5d1cfec64a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfShareCapitalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfShareCapitalAxis_019be683-5f6e-7ff0-bd69-e96dfaeb7ba2" xlink:to="loc_ifrs-full_ClassesOfShareCapitalDomain_019be683-5f6e-7bab-91f1-6a5d1cfec64a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OrdinarySharesMember_019be683-5f6e-7b5f-bfe2-e63fddaed387" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OrdinarySharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfShareCapitalDomain_019be683-5f6e-7bab-91f1-6a5d1cfec64a" xlink:to="loc_ifrs-full_OrdinarySharesMember_019be683-5f6e-7b5f-bfe2-e63fddaed387" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019be683-5f6e-7036-94cc-932385391a11" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019be683-5f6e-701c-b51a-362fb71e13ed" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019be683-5f6e-7036-94cc-932385391a11" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019be683-5f6e-7036-94cc-932385391a11_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019be683-5f6e-7036-94cc-932385391a11" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019be683-5f6e-7036-94cc-932385391a11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019be683-5f6e-7d5a-be27-ed64e3001cfc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019be683-5f6e-7036-94cc-932385391a11" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019be683-5f6e-7d5a-be27-ed64e3001cfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapitalMember_019be683-5f6e-7ed3-8bdf-602dae25d0dd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019be683-5f6e-7d5a-be27-ed64e3001cfc" xlink:to="loc_ifrs-full_IssuedCapitalMember_019be683-5f6e-7ed3-8bdf-602dae25d0dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageShares_019be683-5f6e-7bed-bc0d-893fde8a1add" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019be683-5f6e-79d9-be40-17e3cb60790f" xlink:to="loc_ifrs-full_WeightedAverageShares_019be683-5f6e-7bed-bc0d-893fde8a1add" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquityShareCapitalReserveDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquityShareCapitalReserveDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquityShareCapitalReserveDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-718d-9834-4a471174ba8d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-788b-a491-c724a0276317" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-718d-9834-4a471174ba8d" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-788b-a491-c724a0276317" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7e75-9457-7b6848dafbf1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-788b-a491-c724a0276317" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7e75-9457-7b6848dafbf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7e75-9457-7b6848dafbf1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7e75-9457-7b6848dafbf1" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7e75-9457-7b6848dafbf1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-74c4-80bc-9787a0d2f930" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7e75-9457-7b6848dafbf1" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-74c4-80bc-9787a0d2f930" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CapitalReserveMember_019b0124-055d-7add-ad4c-d59e5088e0ef" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CapitalReserveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-74c4-80bc-9787a0d2f930" xlink:to="loc_ifrs-full_CapitalReserveMember_019b0124-055d-7add-ad4c-d59e5088e0ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ShareCapitalReserveAbstract_019b0124-055d-7040-81e9-b2af349c3220" xlink:href="tlx-20251231.xsd#tlx_ShareCapitalReserveAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-718d-9834-4a471174ba8d" xlink:to="loc_tlx_ShareCapitalReserveAbstract_019b0124-055d-7040-81e9-b2af349c3220" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesIssuedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareCapitalReserveAbstract_019b0124-055d-7040-81e9-b2af349c3220" xlink:to="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-7697-ab5a-4398a88cd142" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:to="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-7697-ab5a-4398a88cd142" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTreasurySharesAcquired_019b0124-055d-71c9-bae0-d908adb28606" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTreasurySharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:to="loc_tlx_IncreaseDecreaseThroughTreasurySharesAcquired_019b0124-055d-71c9-bae0-d908adb28606" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughIssueOfConvertibleBonds_019b0124-055d-7cf5-9ad0-96cc302b5b74" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughIssueOfConvertibleBonds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:to="loc_tlx_IncreaseDecreaseThroughIssueOfConvertibleBonds_019b0124-055d-7cf5-9ad0-96cc302b5b74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssueShares_019b0124-055d-765d-b052-82ed313ca7c9" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssueShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:to="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssueShares_019b0124-055d-765d-b052-82ed313ca7c9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughSharesAllocatedToEmployees_019b0124-055d-775a-aa67-85c6a1d223bd" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughSharesAllocatedToEmployees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NumberOfSharesIssuedAbstract_019be67d-73fc-7784-b2db-fb0abedaeb5d" xlink:to="loc_tlx_IncreaseDecreaseThroughSharesAllocatedToEmployees_019b0124-055d-775a-aa67-85c6a1d223bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-7021-8511-c7f3f9ec12d2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:href="tlx-20251231.xsd#tlx_ValueOfShareholdingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareCapitalReserveAbstract_019b0124-055d-7040-81e9-b2af349c3220" xlink:to="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CapitalReserveDeficit_019b0124-055d-71db-b35e-537f7c89cf4e" xlink:href="tlx-20251231.xsd#tlx_CapitalReserveDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:to="loc_tlx_CapitalReserveDeficit_019b0124-055d-71db-b35e-537f7c89cf4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PurchaseOfTreasuryShares_019b0124-055d-7f00-8cc4-3303d2abe78d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PurchaseOfTreasuryShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:to="loc_ifrs-full_PurchaseOfTreasuryShares_019b0124-055d-7f00-8cc4-3303d2abe78d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssueOfConvertibleInstruments_019b0124-055d-7996-b474-455e9c257a8a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssueOfConvertibleInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:to="loc_ifrs-full_IssueOfConvertibleInstruments_019b0124-055d-7996-b474-455e9c257a8a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue_019b0124-055d-789e-aded-665d85dd265d" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:to="loc_tlx_IncreaseDecreaseThroughTransactionCostsArisingOnConvertibleBondsIssue_019b0124-055d-789e-aded-665d85dd265d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SharesAllocatedToEmployeesValue_019b0124-055d-762c-a0f6-9d8c8c4a6814" xlink:href="tlx-20251231.xsd#tlx_SharesAllocatedToEmployeesValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ValueOfShareholdingAbstract_019be681-22ad-7c0f-a36b-88f74fa10190" xlink:to="loc_tlx_SharesAllocatedToEmployeesValue_019b0124-055d-762c-a0f6-9d8c8c4a6814" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CapitalReserveDeficit_019b0124-055d-7c22-a978-189a66113637" xlink:href="tlx-20251231.xsd#tlx_CapitalReserveDeficit"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquityOtherReservesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquityOtherReservesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquityOtherReservesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7537-8cc2-3eca48d93bcb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7e4a-a436-c4743b359aca" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7537-8cc2-3eca48d93bcb" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7e4a-a436-c4743b359aca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7b48-9aa7-74f420a79f99" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7e4a-a436-c4743b359aca" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7b48-9aa7-74f420a79f99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7b48-9aa7-74f420a79f99_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7b48-9aa7-74f420a79f99" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7b48-9aa7-74f420a79f99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7b48-9aa7-74f420a79f99" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfExchangeDifferencesOnTranslationMember_019b0124-055d-72b4-970d-8b126d963765" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfExchangeDifferencesOnTranslationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:to="loc_ifrs-full_ReserveOfExchangeDifferencesOnTranslationMember_019b0124-055d-72b4-970d-8b126d963765" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfSharebasedPaymentsMember_019b0124-055d-7d91-a048-2f9f70fad3b4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfSharebasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:to="loc_ifrs-full_ReserveOfSharebasedPaymentsMember_019b0124-055d-7d91-a048-2f9f70fad3b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember_019b0124-055d-77a9-b4b4-6926b8672f5d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:to="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember_019b0124-055d-77a9-b4b4-6926b8672f5d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherReservesMember_019b0124-055d-7fc7-8d55-6a893974a8bc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7f07-a26c-c00e1672b1cc" xlink:to="loc_ifrs-full_OtherReservesMember_019b0124-055d-7fc7-8d55-6a893974a8bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:href="tlx-20251231.xsd#tlx_OtherReservesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7537-8cc2-3eca48d93bcb" xlink:to="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019b0124-055d-75b7-b5cc-2b52783eaa53" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_ifrs-full_Equity_019b0124-055d-75b7-b5cc-2b52783eaa53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherComprehensiveIncome_019b3bae-ed2c-7332-b8b0-89a7da073573" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_ifrs-full_OtherComprehensiveIncome_019b3bae-ed2c-7332-b8b0-89a7da073573" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComprehensiveIncome_019b0124-055d-70a5-b825-6e02d6810baf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_ifrs-full_ComprehensiveIncome_019b0124-055d-70a5-b825-6e02d6810baf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions_019b0124-055d-712f-9422-5b201ceb67c8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_ifrs-full_IncreaseDecreaseThroughSharebasedPaymentTransactions_019b0124-055d-712f-9422-5b201ceb67c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity_019b0124-055d-77f3-96e5-0c75a1982375" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_tlx_IncreaseDecreaseThroughShareBasedPaymentTransactionsAssociatedWithAcquisitionsEquity_019b0124-055d-77f3-96e5-0c75a1982375" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRightsEquity_019c4a4a-3734-73f6-a290-ab8b2a77bcaa" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRightsEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_tlx_IncreaseDecreaseThroughTransferOnSatisfactionOfAcquisitionPerformanceRightsEquity_019c4a4a-3734-73f6-a290-ab8b2a77bcaa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity_019b0124-055d-70c1-be74-8e956085c919" xlink:href="tlx-20251231.xsd#tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_tlx_IncreaseDecreaseThroughTransferOnExerciseOfOptionsEquity_019b0124-055d-70c1-be74-8e956085c919" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ChangesInEquity_019b0124-055d-7539-a8ee-3f7a0bd48021" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ChangesInEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_OtherReservesAbstract_019b0124-055d-7acc-8a7f-0367eab86190" xlink:to="loc_ifrs-full_ChangesInEquity_019b0124-055d-7539-a8ee-3f7a0bd48021" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019b0124-055d-7bde-b0c2-5c8d85fcf391" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquitySharebasedPaymentsReserveDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquitySharebasedPaymentsReserveDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquitySharebasedPaymentsReserveDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7147-8f7c-22e58aaf391d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7b85-99fd-f28b73d592e9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7147-8f7c-22e58aaf391d" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7b85-99fd-f28b73d592e9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-77df-a935-0207ae0026b7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-7b85-99fd-f28b73d592e9" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-77df-a935-0207ae0026b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-77df-a935-0207ae0026b7_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-77df-a935-0207ae0026b7" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-77df-a935-0207ae0026b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-783d-9fbe-9e2312de21a7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-77df-a935-0207ae0026b7" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-783d-9fbe-9e2312de21a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfSharebasedPaymentsMember_019b0124-055d-76e9-8cdf-7240c6ae636b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfSharebasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-783d-9fbe-9e2312de21a7" xlink:to="loc_ifrs-full_ReserveOfSharebasedPaymentsMember_019b0124-055d-76e9-8cdf-7240c6ae636b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:href="tlx-20251231.xsd#tlx_ShareBasedPaymentsReserveAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-7147-8f7c-22e58aaf391d" xlink:to="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-72cd-9dd8-90adcfdefbf3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-72cd-9dd8-90adcfdefbf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-7526-be7a-e50512eb67f4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-7526-be7a-e50512eb67f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-7e85-8941-3a0a52ed16d7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-7e85-8941-3a0a52ed16d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement_019b0124-055d-715b-b2d9-e29dfe35e328" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement_019b0124-055d-715b-b2d9-e29dfe35e328" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfPerformanceRightGrantedInShareBasedPaymentArrangement_019b0124-055d-720d-95d5-ec598d82e33c" xlink:href="tlx-20251231.xsd#tlx_NumberOfPerformanceRightGrantedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_tlx_NumberOfPerformanceRightGrantedInShareBasedPaymentArrangement_019b0124-055d-720d-95d5-ec598d82e33c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfPerformanceRightExercisedInShareBasedPaymentArrangement_019c32bd-d47b-7bf8-8e8b-7bd3e0fb4491" xlink:href="tlx-20251231.xsd#tlx_NumberOfPerformanceRightExercisedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_tlx_NumberOfPerformanceRightExercisedInShareBasedPaymentArrangement_019c32bd-d47b-7bf8-8e8b-7bd3e0fb4491" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfPerformanceRightLapsedInShareBasedPaymentArrangement_019c32bd-d47b-720d-ba6d-5bcc9a04f3cd" xlink:href="tlx-20251231.xsd#tlx_NumberOfPerformanceRightLapsedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ShareBasedPaymentsReserveAbstract_019b0124-055d-7344-970e-9f196eb9c351" xlink:to="loc_tlx_NumberOfPerformanceRightLapsedInShareBasedPaymentArrangement_019c32bd-d47b-720d-ba6d-5bcc9a04f3cd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfSharesOutstanding_019b0124-055d-7137-9e97-8754345c3e9e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfSharesOutstanding"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/EquityFinancialAssetsatFVOCIReserveDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#EquityFinancialAssetsatFVOCIReserveDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/EquityFinancialAssetsatFVOCIReserveDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-700e-848e-5c63bd4ca45f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-71a3-8bfb-3c0c12e7ca20" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfClassesOfShareCapitalTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-700e-848e-5c63bd4ca45f" xlink:to="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-71a3-8bfb-3c0c12e7ca20" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7d8f-b767-0e9ae6b3a27f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalTable_019b0124-055d-71a3-8bfb-3c0c12e7ca20" xlink:to="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7d8f-b767-0e9ae6b3a27f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7d8f-b767-0e9ae6b3a27f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7d8f-b767-0e9ae6b3a27f" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7d8f-b767-0e9ae6b3a27f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7cfd-b85c-ef2dd5b12dc9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComponentsOfEquityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ComponentsOfEquityAxis_019b0124-055d-7d8f-b767-0e9ae6b3a27f" xlink:to="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7cfd-b85c-ef2dd5b12dc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember_019b0124-055d-7c21-bf80-190686a2887c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ComponentsOfEquityDomain_019b0124-055d-7cfd-b85c-ef2dd5b12dc9" xlink:to="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember_019b0124-055d-7c21-bf80-190686a2887c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FinancialAssetsAtFVOCIReserveAbstract_019b0124-055d-7234-8d71-e945dff2aef6" xlink:href="tlx-20251231.xsd#tlx_FinancialAssetsAtFVOCIReserveAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfClassesOfShareCapitalLineItems_019b0124-055d-700e-848e-5c63bd4ca45f" xlink:to="loc_tlx_FinancialAssetsAtFVOCIReserveAbstract_019b0124-055d-7234-8d71-e945dff2aef6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome_019b0124-055d-7036-9622-ceecd445dfe0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_FinancialAssetsAtFVOCIReserveAbstract_019b0124-055d-7234-8d71-e945dff2aef6" xlink:to="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome_019b0124-055d-7036-9622-ceecd445dfe0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherComprehensiveIncome_019b0124-055d-7bdc-9162-8149ff01904d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_FinancialAssetsAtFVOCIReserveAbstract_019b0124-055d-7234-8d71-e945dff2aef6" xlink:to="loc_ifrs-full_OtherComprehensiveIncome_019b0124-055d-7bdc-9162-8149ff01904d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxExpenseIncome_019b0124-055d-7f15-bca0-444bf147974f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxExpenseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_FinancialAssetsAtFVOCIReserveAbstract_019b0124-055d-7234-8d71-e945dff2aef6" xlink:to="loc_ifrs-full_DeferredTaxExpenseIncome_019b0124-055d-7f15-bca0-444bf147974f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome_019b0124-055d-7fc5-999b-6887a9f12896" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SharebasedpaymentsScheduleofNumberandWeightedAverageExercisePriceofStockOptionsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SharebasedpaymentsScheduleofNumberandWeightedAverageExercisePriceofStockOptionsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SharebasedpaymentsScheduleofNumberandWeightedAverageExercisePriceofStockOptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019c21f8-cfc6-77a4-878f-92b57927a855" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:to="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019c21f8-cfc6-77a4-878f-92b57927a855" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c21f8-cfc6-7f80-a39e-a5c8f699a78e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019c21f8-cfc6-77a4-878f-92b57927a855" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c21f8-cfc6-7f80-a39e-a5c8f699a78e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7f80-a39e-a5c8f699a78e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c21f8-cfc6-7f80-a39e-a5c8f699a78e" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7f80-a39e-a5c8f699a78e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7d0d-bc6c-dc0542dadfd6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c21f8-cfc6-7f80-a39e-a5c8f699a78e" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7d0d-bc6c-dc0542dadfd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ASXSecuritiesMember_019c21f8-cfc6-7721-819c-cc710d43ba0c" xlink:href="tlx-20251231.xsd#tlx_ASXSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7d0d-bc6c-dc0542dadfd6" xlink:to="loc_tlx_ASXSecuritiesMember_019c21f8-cfc6-7721-819c-cc710d43ba0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ADSBackedSecuritiesMember_019c21fb-5216-7ab8-838a-5b7eb7e302d7" xlink:href="tlx-20251231.xsd#tlx_ADSBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c21f8-cfc6-7d0d-bc6c-dc0542dadfd6" xlink:to="loc_tlx_ADSBackedSecuritiesMember_019c21fb-5216-7ab8-838a-5b7eb7e302d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:href="tlx-20251231.xsd#tlx_NumberOfOptionsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:to="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-7aff-8bdf-5d7ce1fe2cd2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:to="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-7aff-8bdf-5d7ce1fe2cd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-790a-b352-cf0ea8c4de72" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:to="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-790a-b352-cf0ea8c4de72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-7cdd-a1ee-7263dc5c9def" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:to="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-7cdd-a1ee-7263dc5c9def" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement_019b0124-055d-7400-a3e1-c342ee0f1805" xlink:href="tlx-20251231.xsd#tlx_NumberOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsAbstract_019b0124-055d-75be-aa39-886ef2fcf174" xlink:to="loc_tlx_NumberOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement_019b0124-055d-7400-a3e1-c342ee0f1805" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-76d8-b160-8722086dc7b0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement_019b0124-055d-7601-aece-9e37bf1a74c1" xlink:href="tlx-20251231.xsd#tlx_NumberOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:to="loc_tlx_NumberOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement_019b0124-055d-7601-aece-9e37bf1a74c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:href="tlx-20251231.xsd#tlx_WeightedAverageExercisePriceAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:to="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019_019b0124-055d-7b17-aa08-647cd7d90930" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:to="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019_019b0124-055d-7b17-aa08-647cd7d90930" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement2019_019b0124-055d-7493-a574-00d35c6b8e38" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:to="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement2019_019b0124-055d-7493-a574-00d35c6b8e38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019_019b0124-055d-7bf3-b60c-2798590927d0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:to="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019_019b0124-055d-7bf3-b60c-2798590927d0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WeightedAverageExercisePriceOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement_019b0124-055d-7f3b-a73c-92a5a7861827" xlink:href="tlx-20251231.xsd#tlx_WeightedAverageExercisePriceOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_WeightedAverageExercisePriceAbstract_019b0124-055d-752f-8c2e-469388150d3c" xlink:to="loc_tlx_WeightedAverageExercisePriceOfShareOptionsExpiredAndForfeitedInShareBasedPaymentArrangement_019b0124-055d-7f3b-a73c-92a5a7861827" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019_019b0124-055d-7e25-b5e9-a9bb643b2ab2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_WeightedAverageExercisePriceOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement_019b0124-055d-7ba8-80da-a9281b2532dd" xlink:href="tlx-20251231.xsd#tlx_WeightedAverageExercisePriceOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019c21f9-a929-7c46-be59-eaa92027721f" xlink:to="loc_tlx_WeightedAverageExercisePriceOfShareOptionsVestedAndExercisableInShareBasedPaymentArrangement_019b0124-055d-7ba8-80da-a9281b2532dd" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SharebasedpaymentsScheduleofNumberofOptionsIssuedunderEquityIncentivePlanOutstandingDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SharebasedpaymentsScheduleofNumberofOptionsIssuedunderEquityIncentivePlanOutstandingDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SharebasedpaymentsScheduleofNumberofOptionsIssuedunderEquityIncentivePlanOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-74ba-83c4-230065c07198" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-70cc-8b56-e389072fe84e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-74ba-83c4-230065c07198" xlink:to="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-70cc-8b56-e389072fe84e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateAxis_019b0124-055d-7df5-ad00-a54f0f368788" xlink:href="tlx-20251231.xsd#tlx_GrantDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-70cc-8b56-e389072fe84e" xlink:to="loc_tlx_GrantDateAxis_019b0124-055d-7df5-ad00-a54f0f368788" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateDomain_019b0124-055d-7df5-ad00-a54f0f368788_default" xlink:href="tlx-20251231.xsd#tlx_GrantDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_GrantDateAxis_019b0124-055d-7df5-ad00-a54f0f368788" xlink:to="loc_tlx_GrantDateDomain_019b0124-055d-7df5-ad00-a54f0f368788_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateDomain_019bea5b-90f7-767d-8de0-3b0a27a28d9c" xlink:href="tlx-20251231.xsd#tlx_GrantDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_GrantDateAxis_019b0124-055d-7df5-ad00-a54f0f368788" xlink:to="loc_tlx_GrantDateDomain_019bea5b-90f7-767d-8de0-3b0a27a28d9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DefaultFinancialStatementsDateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_GrantDateDomain_019bea5b-90f7-767d-8de0-3b0a27a28d9c" xlink:to="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateJanuary272021Member_019bea4e-de94-7ffe-af55-f3394c99b554" xlink:href="tlx-20251231.xsd#tlx_GrantDateJanuary272021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateJanuary272021Member_019bea4e-de94-7ffe-af55-f3394c99b554" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateJuly272021Member_019bea4f-aa06-73f9-bf53-0682333cb27e" xlink:href="tlx-20251231.xsd#tlx_GrantDateJuly272021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateJuly272021Member_019bea4f-aa06-73f9-bf53-0682333cb27e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateApril52022Member_019bea50-c6e2-7c15-8b2c-ea625c81f1db" xlink:href="tlx-20251231.xsd#tlx_GrantDateApril52022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateApril52022Member_019bea50-c6e2-7c15-8b2c-ea625c81f1db" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateOctober242022Member_019bea51-c1ef-770a-bfe6-b00f0b017c4c" xlink:href="tlx-20251231.xsd#tlx_GrantDateOctober242022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateOctober242022Member_019bea51-c1ef-770a-bfe6-b00f0b017c4c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateMay22023Member_019bea52-16d6-7f77-9f3d-6f535c352f83" xlink:href="tlx-20251231.xsd#tlx_GrantDateMay22023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateMay22023Member_019bea52-16d6-7f77-9f3d-6f535c352f83" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateMay222024Member_019bea52-81df-7957-929b-52f0b96e9ed7" xlink:href="tlx-20251231.xsd#tlx_GrantDateMay222024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateMay222024Member_019bea52-81df-7957-929b-52f0b96e9ed7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateJuly62023Member_019bea52-e430-7179-8be6-e8951aafe0f2" xlink:href="tlx-20251231.xsd#tlx_GrantDateJuly62023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateJuly62023Member_019bea52-e430-7179-8be6-e8951aafe0f2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateOctober182023Member_019bea53-38aa-7f82-a5ef-fabc222ca3a1" xlink:href="tlx-20251231.xsd#tlx_GrantDateOctober182023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateOctober182023Member_019bea53-38aa-7f82-a5ef-fabc222ca3a1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateOctober312023Member_019bea53-9c80-725f-9a6b-457106ec5a44" xlink:href="tlx-20251231.xsd#tlx_GrantDateOctober312023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateOctober312023Member_019bea53-9c80-725f-9a6b-457106ec5a44" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateNovember302023Member_019bea54-702e-72a9-8e65-e0d69cbb88ca" xlink:href="tlx-20251231.xsd#tlx_GrantDateNovember302023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateNovember302023Member_019bea54-702e-72a9-8e65-e0d69cbb88ca" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateMarch82024Member_019bea54-cc5a-7930-995b-fead9a3ce00b" xlink:href="tlx-20251231.xsd#tlx_GrantDateMarch82024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateMarch82024Member_019bea54-cc5a-7930-995b-fead9a3ce00b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateMay2220241Member_019bea58-ec6c-72e8-b737-745254f3d1e2" xlink:href="tlx-20251231.xsd#tlx_GrantDateMay2220241Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateMay2220241Member_019bea58-ec6c-72e8-b737-745254f3d1e2" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateApril262024Member_019bea5a-0a33-7e4c-92ec-cedd44fd6c77" xlink:href="tlx-20251231.xsd#tlx_GrantDateApril262024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateApril262024Member_019bea5a-0a33-7e4c-92ec-cedd44fd6c77" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateAugust262024Member_019bea5a-dc74-7acf-a589-2dff90a34a71" xlink:href="tlx-20251231.xsd#tlx_GrantDateAugust262024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateAugust262024Member_019bea5a-dc74-7acf-a589-2dff90a34a71" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateSeptember192024Member_019bea5b-ec03-73a6-917e-4b7808d4a709" xlink:href="tlx-20251231.xsd#tlx_GrantDateSeptember192024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateSeptember192024Member_019bea5b-ec03-73a6-917e-4b7808d4a709" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateOctober172024Member_019c12d0-d4f8-79b3-8b3d-2810b107277c" xlink:href="tlx-20251231.xsd#tlx_GrantDateOctober172024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateOctober172024Member_019c12d0-d4f8-79b3-8b3d-2810b107277c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateJanuary12025Member_019c12d1-d9f1-7c3b-8d15-2c0105332e64" xlink:href="tlx-20251231.xsd#tlx_GrantDateJanuary12025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateJanuary12025Member_019c12d1-d9f1-7c3b-8d15-2c0105332e64" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateOctober242025Member_019c12d2-928b-7acf-9b73-22e06215eed8" xlink:href="tlx-20251231.xsd#tlx_GrantDateOctober242025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateOctober242025Member_019c12d2-928b-7acf-9b73-22e06215eed8" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GrantDateMarch172025Member_019c12d3-513c-7414-bcd3-a98b62df340b" xlink:href="tlx-20251231.xsd#tlx_GrantDateMarch172025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DefaultFinancialStatementsDateMember_019b0124-055d-7427-be1b-22271e23dbb5" xlink:to="loc_tlx_GrantDateMarch172025Member_019c12d3-513c-7414-bcd3-a98b62df340b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheAxis_019bfd5d-60b6-7399-8ae3-f7ed00a12e92" xlink:href="tlx-20251231.xsd#tlx_TrancheAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-70cc-8b56-e389072fe84e" xlink:to="loc_tlx_TrancheAxis_019bfd5d-60b6-7399-8ae3-f7ed00a12e92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019bfd5d-60b6-7399-8ae3-f7ed00a12e92_default" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_TrancheAxis_019bfd5d-60b6-7399-8ae3-f7ed00a12e92" xlink:to="loc_tlx_TrancheDomain_019bfd5d-60b6-7399-8ae3-f7ed00a12e92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019bfd5d-60b6-7e93-b338-d2f162c86d41" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_TrancheAxis_019bfd5d-60b6-7399-8ae3-f7ed00a12e92" xlink:to="loc_tlx_TrancheDomain_019bfd5d-60b6-7e93-b338-d2f162c86d41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheOneMember_019bfd5e-1bae-710c-9d23-aa645bca692e" xlink:href="tlx-20251231.xsd#tlx_TrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019bfd5d-60b6-7e93-b338-d2f162c86d41" xlink:to="loc_tlx_TrancheOneMember_019bfd5e-1bae-710c-9d23-aa645bca692e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheTwoMember_019bfd5e-9e5c-7520-8b57-28aa247d9e82" xlink:href="tlx-20251231.xsd#tlx_TrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019bfd5d-60b6-7e93-b338-d2f162c86d41" xlink:to="loc_tlx_TrancheTwoMember_019bfd5e-9e5c-7520-8b57-28aa247d9e82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c220b-d15c-76eb-aafb-eb681f7b7a7e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-70cc-8b56-e389072fe84e" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c220b-d15c-76eb-aafb-eb681f7b7a7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-76eb-aafb-eb681f7b7a7e_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c220b-d15c-76eb-aafb-eb681f7b7a7e" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-76eb-aafb-eb681f7b7a7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-77c3-a3fe-8c115d0274cc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c220b-d15c-76eb-aafb-eb681f7b7a7e" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-77c3-a3fe-8c115d0274cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ASXSecuritiesMember_019c220b-d15c-7d4b-89c8-7a18992b82bf" xlink:href="tlx-20251231.xsd#tlx_ASXSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-77c3-a3fe-8c115d0274cc" xlink:to="loc_tlx_ASXSecuritiesMember_019c220b-d15c-7d4b-89c8-7a18992b82bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ADSBackedSecuritiesMember_019c220c-048c-7d7f-94af-bf79e2ad4b29" xlink:href="tlx-20251231.xsd#tlx_ADSBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c220b-d15c-77c3-a3fe-8c115d0274cc" xlink:to="loc_tlx_ADSBackedSecuritiesMember_019c220c-048c-7d7f-94af-bf79e2ad4b29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:href="tlx-20251231.xsd#tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-74ba-83c4-230065c07198" xlink:to="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019_019b0124-055d-7694-ab54-da012de8cf89" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement2019_019b0124-055d-7694-ab54-da012de8cf89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-7542-ae02-e4293a626791" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-7542-ae02-e4293a626791" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-7c51-932d-cd652e3c8cdb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement_019b0124-055d-7c51-932d-cd652e3c8cdb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NumberOfShareOptionsVestedInShareBasedPaymentArrangement_019b0124-055d-70ee-a6f0-874484b85d20" xlink:href="tlx-20251231.xsd#tlx_NumberOfShareOptionsVestedInShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_tlx_NumberOfShareOptionsVestedInShareBasedPaymentArrangement_019b0124-055d-70ee-a6f0-874484b85d20" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-75d2-a6a5-d031ff75bd6f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_ifrs-full_NumberOfShareOptionsExercisedInSharebasedPaymentArrangement_019b0124-055d-75d2-a6a5-d031ff75bd6f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfShareOptionsExpiredInSharebasedPaymentArrangement_019b0124-055d-7266-9391-f28d208e92e8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfShareOptionsExpiredInSharebasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_NumberOfOptionsIssuedUnderEquityIncentivePlanAbstract_019b0124-055d-75d4-863a-35cde350c6fd" xlink:to="loc_ifrs-full_NumberOfShareOptionsExpiredInSharebasedPaymentArrangement_019b0124-055d-7266-9391-f28d208e92e8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NumberOfOutstandingShareOptions_019b0124-055d-70c6-bf02-a9a1bfc75ced" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/SharebasedpaymentsScheduleofFairValueofGrantDateInputsforOptionsGrantedDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#SharebasedpaymentsScheduleofFairValueofGrantDateInputsforOptionsGrantedDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/SharebasedpaymentsScheduleofFairValueofGrantDateInputsforOptionsGrantedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-7c6f-9b66-ff3b5a02aa31" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-7c6f-9b66-ff3b5a02aa31" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheAxis_019c3063-db86-75f9-8647-a5017e832ff4" xlink:href="tlx-20251231.xsd#tlx_TrancheAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-7c6f-9b66-ff3b5a02aa31" xlink:to="loc_tlx_TrancheAxis_019c3063-db86-75f9-8647-a5017e832ff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019c3063-db86-75f9-8647-a5017e832ff4_default" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_TrancheAxis_019c3063-db86-75f9-8647-a5017e832ff4" xlink:to="loc_tlx_TrancheDomain_019c3063-db86-75f9-8647-a5017e832ff4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TrancheDomain_019c3063-db86-7b99-963d-96ba4e141c88" xlink:href="tlx-20251231.xsd#tlx_TrancheDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_TrancheAxis_019c3063-db86-75f9-8647-a5017e832ff4" xlink:to="loc_tlx_TrancheDomain_019c3063-db86-7b99-963d-96ba4e141c88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FirstTrancheMember_019c3064-0fb7-797d-abee-1b2b9b8881c0" xlink:href="tlx-20251231.xsd#tlx_FirstTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019c3063-db86-7b99-963d-96ba4e141c88" xlink:to="loc_tlx_FirstTrancheMember_019c3064-0fb7-797d-abee-1b2b9b8881c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SecondTrancheMember_019c3064-3e12-719d-a487-1d49ea6ca80f" xlink:href="tlx-20251231.xsd#tlx_SecondTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_TrancheDomain_019c3063-db86-7b99-963d-96ba4e141c88" xlink:to="loc_tlx_SecondTrancheMember_019c3064-3e12-719d-a487-1d49ea6ca80f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c310f-0c45-7da1-affc-61e2d785e743" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable_019b0124-055d-7c6f-9b66-ff3b5a02aa31" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c310f-0c45-7da1-affc-61e2d785e743" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-7da1-affc-61e2d785e743_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c310f-0c45-7da1-affc-61e2d785e743" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-7da1-affc-61e2d785e743_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-73e2-b008-6bd9b8525754" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsAxis_019c310f-0c45-7da1-affc-61e2d785e743" xlink:to="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-73e2-b008-6bd9b8525754" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ASXSecuritiesMember_019c310f-0c45-70f5-a0a9-ab7e38aa384e" xlink:href="tlx-20251231.xsd#tlx_ASXSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-73e2-b008-6bd9b8525754" xlink:to="loc_tlx_ASXSecuritiesMember_019c310f-0c45-70f5-a0a9-ab7e38aa384e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ADSBackedSecuritiesMember_019c3110-4f23-7387-b530-b847e8476eca" xlink:href="tlx-20251231.xsd#tlx_ADSBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfSharebasedPaymentArrangementsDomain_019c310f-0c45-73e2-b008-6bd9b8525754" xlink:to="loc_tlx_ADSBackedSecuritiesMember_019c3110-4f23-7387-b530-b847e8476eca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_FairValueStockOptionsGranted_019b0124-055d-7f1f-a9f5-bea659b21b4a" xlink:href="tlx-20251231.xsd#tlx_FairValueStockOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_tlx_FairValueStockOptionsGranted_019b0124-055d-7f1f-a9f5-bea659b21b4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ConsiderationShareOptionsGranted_019b0124-055d-712f-988a-a0038e6d31c5" xlink:href="tlx-20251231.xsd#tlx_ConsiderationShareOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_tlx_ConsiderationShareOptionsGranted_019b0124-055d-712f-988a-a0038e6d31c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ExercisePriceShareOptionsGranted2019_019b0124-055d-7839-850f-f182fb93c2a7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ExercisePriceShareOptionsGranted2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_ExercisePriceShareOptionsGranted2019_019b0124-055d-7839-850f-f182fb93c2a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfOptionLifeShareOptionsGranted_019b0124-055d-7478-b1e6-7de1a3e26a0f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfOptionLifeShareOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_DescriptionOfOptionLifeShareOptionsGranted_019b0124-055d-7478-b1e6-7de1a3e26a0f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019_019b0124-055d-78f4-ae81-cf79a09f51aa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019_019b0124-055d-78f4-ae81-cf79a09f51aa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted_019b0124-055d-7cd9-93b2-90a7e51b2eba" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted_019b0124-055d-7cd9-93b2-90a7e51b2eba" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted_019b0124-055d-72d5-8d4e-9e45291044c0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted_019b0124-055d-72d5-8d4e-9e45291044c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted_019b0124-055d-7fac-9592-3008398baabf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems_019b0124-055d-7e77-b301-4df974fefeee" xlink:to="loc_ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted_019b0124-055d-7fac-9592-3008398baabf" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialriskmanagementNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialriskmanagementNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialriskmanagementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7754-ba6f-a542cd8dd1f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7754-ba6f-a542cd8dd1f8" xlink:to="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-78e1-9372-8769f1787613" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-78e1-9372-8769f1787613" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-78e1-9372-8769f1787613_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-78e1-9372-8769f1787613" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-78e1-9372-8769f1787613_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-78df-9c80-50f7e5db884f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-78e1-9372-8769f1787613" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-78df-9c80-50f7e5db884f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrencyRiskMember_019b0124-055d-7be9-933c-96329ed148cd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrencyRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-78df-9c80-50f7e5db884f" xlink:to="loc_ifrs-full_CurrencyRiskMember_019b0124-055d-7be9-933c-96329ed148cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CurrencyAxis_019b0124-055d-724a-a9d9-ed8fe57cae7c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CurrencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_srt_CurrencyAxis_019b0124-055d-724a-a9d9-ed8fe57cae7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019b0124-055d-724a-a9d9-ed8fe57cae7c_default" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CurrencyAxis_019b0124-055d-724a-a9d9-ed8fe57cae7c" xlink:to="loc_currency_AllCurrenciesDomain_019b0124-055d-724a-a9d9-ed8fe57cae7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CurrencyAxis_019b0124-055d-724a-a9d9-ed8fe57cae7c" xlink:to="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AUD_019b0124-055d-7993-a077-ce3b6512d5b2" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AUD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_AUD_019b0124-055d-7993-a077-ce3b6512d5b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_USD_019b0124-055d-7939-9c2d-9a4c233a0769" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_USD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_USD_019b0124-055d-7939-9c2d-9a4c233a0769" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_EUR_019b0124-055d-77c9-9414-8797d994006b" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_EUR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_EUR_019b0124-055d-77c9-9414-8797d994006b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_JPY_019b0124-055d-749c-a423-90a12a862fd2" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_JPY"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_JPY_019b0124-055d-749c-a423-90a12a862fd2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_GBP_019b0124-055d-71e9-b78e-b4f6c4790039" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_GBP"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_GBP_019b0124-055d-71e9-b78e-b4f6c4790039" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CAD_019b0124-055d-79f7-8c37-1c09238e1279" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CAD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_CAD_019b0124-055d-79f7-8c37-1c09238e1279" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CHF_019b0124-055d-74e4-bf86-703fd570bcf6" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CHF"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019b0124-055d-7396-9541-c9afc84f4dcf" xlink:to="loc_currency_CHF_019b0124-055d-74e4-bf86-703fd570bcf6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LevelsOfFairValueHierarchyAxis_019be614-d33c-7d67-91e7-37a509fc4995" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LevelsOfFairValueHierarchyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_ifrs-full_LevelsOfFairValueHierarchyAxis_019be614-d33c-7d67-91e7-37a509fc4995" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-7d67-91e7-37a509fc4995_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LevelsOfFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_LevelsOfFairValueHierarchyAxis_019be614-d33c-7d67-91e7-37a509fc4995" xlink:to="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-7d67-91e7-37a509fc4995_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-72df-9f7a-d50192974360" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LevelsOfFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_LevelsOfFairValueHierarchyAxis_019be614-d33c-7d67-91e7-37a509fc4995" xlink:to="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-72df-9f7a-d50192974360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Level3OfFairValueHierarchyMember_019be614-d33c-72bf-b7f2-715eb7dad027" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Level3OfFairValueHierarchyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-72df-9f7a-d50192974360" xlink:to="loc_ifrs-full_Level3OfFairValueHierarchyMember_019be614-d33c-72bf-b7f2-715eb7dad027" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Level1OfFairValueHierarchyMember_019bea36-2a73-72a9-8fe3-af20c276b56d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Level1OfFairValueHierarchyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LevelsOfFairValueHierarchyDomain_019be614-d33c-72df-9f7a-d50192974360" xlink:to="loc_ifrs-full_Level1OfFairValueHierarchyMember_019bea36-2a73-72a9-8fe3-af20c276b56d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9d7-bf59-799d-b71f-9c118d1c8501" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9d7-bf59-799d-b71f-9c118d1c8501" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be9d7-bf59-799d-b71f-9c118d1c8501_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9d7-bf59-799d-b71f-9c118d1c8501" xlink:to="loc_ifrs-full_CarryingAmountMember_019be9d7-bf59-799d-b71f-9c118d1c8501_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be9d7-bf59-7131-99f6-9154a0fa84db" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9d7-bf59-799d-b71f-9c118d1c8501" xlink:to="loc_ifrs-full_CarryingAmountMember_019be9d7-bf59-7131-99f6-9154a0fa84db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedImpairmentMember_019be9d8-02ae-7fa4-bc67-d8bd22a45dea" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedImpairmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be9d7-bf59-7131-99f6-9154a0fa84db" xlink:to="loc_ifrs-full_AccumulatedImpairmentMember_019be9d8-02ae-7fa4-bc67-d8bd22a45dea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9d8-7ed7-7f64-8929-7b8783d42a4b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9d8-7ed7-7ace-b01f-b1bebacc7dbd" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9d8-7ed7-7f64-8929-7b8783d42a4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeReceivablesMember_019be9d8-c050-7fc5-b86b-331074ed8db6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9d8-7ed7-7f64-8929-7b8783d42a4b" xlink:to="loc_ifrs-full_TradeReceivablesMember_019be9d8-c050-7fc5-b86b-331074ed8db6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementAxis_019bea36-2a74-7b19-8ecc-40ac8141580f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ValuationTechniquesUsedInFairValueMeasurementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-73c8-9e18-466b187472c7" xlink:to="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementAxis_019bea36-2a74-7b19-8ecc-40ac8141580f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-7b19-8ecc-40ac8141580f_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementAxis_019bea36-2a74-7b19-8ecc-40ac8141580f" xlink:to="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-7b19-8ecc-40ac8141580f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-723d-9da3-fa19914f99b8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementAxis_019bea36-2a74-7b19-8ecc-40ac8141580f" xlink:to="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-723d-9da3-fa19914f99b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MarketApproachMember_019bea36-2a74-7e20-8ee7-e868eb5c490a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MarketApproachMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-723d-9da3-fa19914f99b8" xlink:to="loc_ifrs-full_MarketApproachMember_019bea36-2a74-7e20-8ee7-e868eb5c490a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DiscountedCashFlowMember_019bea36-ce30-7aaf-8e44-9b1f55069639" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ValuationTechniquesUsedInFairValueMeasurementDomain_019bea36-2a74-723d-9da3-fa19914f99b8" xlink:to="loc_ifrs-full_DiscountedCashFlowMember_019bea36-ce30-7aaf-8e44-9b1f55069639" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:href="tlx-20251231.xsd#tlx_ForeignCurrencyRiskAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7754-ba6f-a542cd8dd1f8" xlink:to="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SurplusOfForeignCurrencyReceivablesAndFinancialAssetsOverPayables_019b0124-055d-7d57-94f0-1598bb3b9c76" xlink:href="tlx-20251231.xsd#tlx_SurplusOfForeignCurrencyReceivablesAndFinancialAssetsOverPayables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_tlx_SurplusOfForeignCurrencyReceivablesAndFinancialAssetsOverPayables_019b0124-055d-7d57-94f0-1598bb3b9c76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PercentageOfCashHeldInForeignCurrency_019b0124-055d-762a-8630-6292a937d335" xlink:href="tlx-20251231.xsd#tlx_PercentageOfCashHeldInForeignCurrency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_tlx_PercentageOfCashHeldInForeignCurrency_019b0124-055d-762a-8630-6292a937d335" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialAssets_019be614-5ba3-7c78-a651-79d8e241ce0b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_FinancialAssets_019be614-5ba3-7c78-a651-79d8e241ce0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SignificantCreditRiskExposureNumberOfDistributors_019be614-922c-7895-b8a6-50406e0930a6" xlink:href="tlx-20251231.xsd#tlx_SignificantCreditRiskExposureNumberOfDistributors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_tlx_SignificantCreditRiskExposureNumberOfDistributors_019be614-922c-7895-b8a6-50406e0930a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SignificantCreditRiskExposureRiskPercentage_019be614-922c-72bc-9ff9-0483fdc5f660" xlink:href="tlx-20251231.xsd#tlx_SignificantCreditRiskExposureRiskPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_tlx_SignificantCreditRiskExposureRiskPercentage_019be614-922c-72bc-9ff9-0483fdc5f660" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_MajorRiskThresholdPercentageOfTotalClassOfAsset_019be614-922c-781b-99e0-d0eca7fc03f9" xlink:href="tlx-20251231.xsd#tlx_MajorRiskThresholdPercentageOfTotalClassOfAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_tlx_MajorRiskThresholdPercentageOfTotalClassOfAsset_019be614-922c-781b-99e0-d0eca7fc03f9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputAssets_019bea36-2a74-7c1e-a974-97727c06aa68" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputAssets_019bea36-2a74-7c1e-a974-97727c06aa68" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputAssets_019bea36-2a74-766c-ba25-55eeb17d6b4c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputAssets_019bea36-2a74-766c-ba25-55eeb17d6b4c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets_019bea36-ce30-7d06-a3ee-9e4199b222c8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets_019bea36-ce30-7d06-a3ee-9e4199b222c8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets_019bfd77-53cd-7a39-8692-b1988f300e3d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInOtherComprehensiveIncomeAfterTaxAssets_019bfd77-53cd-7a39-8692-b1988f300e3d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities_019be614-d33c-746f-8d2d-59692fcdca6c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleIncreaseInUnobservableInputLiabilities_019be614-d33c-746f-8d2d-59692fcdca6c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities_019be614-d33c-7899-8f6d-5668d4088ce1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_PercentageOfReasonablyPossibleDecreaseInUnobservableInputLiabilities_019be614-d33c-7899-8f6d-5668d4088ce1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInProfitOrLossBeforeTaxLiabilities_019be614-d33c-778b-a859-17649b16d1a9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInProfitOrLossBeforeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleIncreaseInUnobservableInputRecognisedInProfitOrLossBeforeTaxLiabilities_019be614-d33c-778b-a859-17649b16d1a9" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInProfitOrLossAfterTaxLiabilities_019bfd7b-abb3-7af1-9632-866e29141e13" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInProfitOrLossAfterTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ForeignCurrencyRiskAbstract_019b0124-055d-730c-9def-c1479723c168" xlink:to="loc_ifrs-full_IncreaseDecreaseInFairValueMeasurementDueToReasonablyPossibleDecreaseInUnobservableInputRecognisedInProfitOrLossAfterTaxLiabilities_019bfd7b-abb3-7af1-9632-866e29141e13" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialriskmanagementCurrencyRiskDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialriskmanagementCurrencyRiskDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialriskmanagementCurrencyRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019be603-7948-7b6b-87d7-4a405043677a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019be603-7948-7b6b-87d7-4a405043677a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CurrencyAxis_019be603-7948-7ddb-895a-c7ec22f4b39c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CurrencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019be603-7948-7b6b-87d7-4a405043677a" xlink:to="loc_srt_CurrencyAxis_019be603-7948-7ddb-895a-c7ec22f4b39c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019be603-7948-7ddb-895a-c7ec22f4b39c_default" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CurrencyAxis_019be603-7948-7ddb-895a-c7ec22f4b39c" xlink:to="loc_currency_AllCurrenciesDomain_019be603-7948-7ddb-895a-c7ec22f4b39c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CurrencyAxis_019be603-7948-7ddb-895a-c7ec22f4b39c" xlink:to="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_USD_019be603-7948-77e4-9c68-a4cb2c6102fa" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_USD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_USD_019be603-7948-77e4-9c68-a4cb2c6102fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AUD_019be603-7948-75eb-8366-3e1984a538a7" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AUD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_AUD_019be603-7948-75eb-8366-3e1984a538a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_EUR_019be603-7948-7f6b-b1c1-00555b66a6bb" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_EUR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_EUR_019be603-7948-7f6b-b1c1-00555b66a6bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CHF_019be603-7948-7479-8a0a-42ce9aa1672f" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CHF"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_CHF_019be603-7948-7479-8a0a-42ce9aa1672f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_JPY_019be603-7948-77fe-9eea-5a783be12e8b" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_JPY"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_JPY_019be603-7948-77fe-9eea-5a783be12e8b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_GBP_019be603-7948-7797-9fc5-fdc054d7fa06" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_GBP"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_GBP_019be603-7948-7797-9fc5-fdc054d7fa06" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CAD_019be603-7948-76a5-95b6-773b7b9b1014" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CAD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019be603-7948-7c7f-afb1-205502e63aa0" xlink:to="loc_currency_CAD_019be603-7948-76a5-95b6-773b7b9b1014" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksAxis_019be603-7948-7c97-87b4-686233fbfbb1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019be603-7948-7b6b-87d7-4a405043677a" xlink:to="loc_ifrs-full_TypesOfRisksAxis_019be603-7948-7c97-87b4-686233fbfbb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019be603-7948-7c97-87b4-686233fbfbb1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019be603-7948-7c97-87b4-686233fbfbb1" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019be603-7948-7c97-87b4-686233fbfbb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019be603-7948-7038-969d-a5f01c8e0b0a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019be603-7948-7c97-87b4-686233fbfbb1" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019be603-7948-7038-969d-a5f01c8e0b0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrencyRiskMember_019be603-7948-751b-b430-15e3feff1acc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrencyRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfRisksDomain_019be603-7948-7038-969d-a5f01c8e0b0a" xlink:to="loc_ifrs-full_CurrencyRiskMember_019be603-7948-751b-b430-15e3feff1acc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashAndCashEquivalents_019be603-7948-796f-97ee-09d359618ac5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_CashAndCashEquivalents_019be603-7948-796f-97ee-09d359618ac5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeReceivables_019be603-7948-76ae-bd3f-8da93c9c934f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_TradeReceivables_019be603-7948-76ae-bd3f-8da93c9c934f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialAssets_019be603-7948-7b38-a04b-0c303b82c39e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_FinancialAssets_019be603-7948-7b38-a04b-0c303b82c39e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherPayablesToTradeSuppliers_019be603-7948-7d48-a965-da42aae529b6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherPayablesToTradeSuppliers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_TradeAndOtherPayablesToTradeSuppliers_019be603-7948-7d48-a965-da42aae529b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherCurrentLiabilities_019c3317-ddda-75f8-8e78-173b7454a5f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_OtherCurrentLiabilities_019c3317-ddda-75f8-8e78-173b7454a5f8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherNoncurrentLiabilities_019c3318-f029-7fa3-9a12-032626c3b753" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_OtherNoncurrentLiabilities_019c3318-f029-7fa3-9a12-032626c3b753" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GovernmentGrants_019be603-7948-7450-9dd7-820debed5a35" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GovernmentGrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_GovernmentGrants_019be603-7948-7450-9dd7-820debed5a35" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCosts_019be603-7948-7860-8ee2-3a7a035b4452" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCosts_019be603-7948-7860-8ee2-3a7a035b4452" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentConsideration_019be603-7948-7de7-9378-9c8ff7d15983" xlink:href="tlx-20251231.xsd#tlx_ContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_tlx_ContingentConsideration_019be603-7948-7de7-9378-9c8ff7d15983" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019be603-7948-7a07-b8f2-ccc6f96d7f11" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019be603-7948-76c1-967f-aa7ef8ca50f8" xlink:to="loc_ifrs-full_Borrowings_019be603-7948-7a07-b8f2-ccc6f96d7f11" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialriskmanagementSensitivityDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialriskmanagementSensitivityDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialriskmanagementSensitivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfCreditRiskExposureLineItems_019bea1c-d31a-76f7-99ff-2a459123ec64" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfCreditRiskExposureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfCreditRiskExposureTable_019bea1c-d319-7930-aa5e-d02b1693bda2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfCreditRiskExposureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureLineItems_019bea1c-d31a-76f7-99ff-2a459123ec64" xlink:to="loc_ifrs-full_DisclosureOfCreditRiskExposureTable_019bea1c-d319-7930-aa5e-d02b1693bda2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CurrencyAxis_019bea1c-d31a-7d5e-ba1b-013df3c38cb3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CurrencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureTable_019bea1c-d319-7930-aa5e-d02b1693bda2" xlink:to="loc_srt_CurrencyAxis_019bea1c-d31a-7d5e-ba1b-013df3c38cb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019bea1c-d31a-7d5e-ba1b-013df3c38cb3_default" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CurrencyAxis_019bea1c-d31a-7d5e-ba1b-013df3c38cb3" xlink:to="loc_currency_AllCurrenciesDomain_019bea1c-d31a-7d5e-ba1b-013df3c38cb3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AllCurrenciesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CurrencyAxis_019bea1c-d31a-7d5e-ba1b-013df3c38cb3" xlink:to="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_AUD_019bea1c-d31a-72c5-9403-23b60066ba91" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_AUD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_AUD_019bea1c-d31a-72c5-9403-23b60066ba91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_EUR_019bea1c-d31a-7b43-a7df-bfc54d44c189" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_EUR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_EUR_019bea1c-d31a-7b43-a7df-bfc54d44c189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CHF_019bea1c-d31a-7e73-83c8-8b6a18f2d526" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CHF"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_CHF_019bea1c-d31a-7e73-83c8-8b6a18f2d526" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_JPY_019bea1c-d31a-755e-864e-4d15d06fc3f8" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_JPY"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_JPY_019bea1c-d31a-755e-864e-4d15d06fc3f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_GBP_019bea1c-d31a-7fc2-a6b8-f8deb79be0e4" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_GBP"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_GBP_019bea1c-d31a-7fc2-a6b8-f8deb79be0e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_currency_CAD_019bea1c-d31a-74f9-aa46-3566ca57b24f" xlink:href="https://xbrl.sec.gov/currency/2025/currency-2025.xsd#currency_CAD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_currency_AllCurrenciesDomain_019bea1c-d31a-749f-860b-30e55f5ca040" xlink:to="loc_currency_CAD_019bea1c-d31a-74f9-aa46-3566ca57b24f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksAxis_019bea1c-d31a-7fd6-9136-48d7bf907ca2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureTable_019bea1c-d319-7930-aa5e-d02b1693bda2" xlink:to="loc_ifrs-full_TypesOfRisksAxis_019bea1c-d31a-7fd6-9136-48d7bf907ca2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019bea1c-d31a-7fd6-9136-48d7bf907ca2_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019bea1c-d31a-7fd6-9136-48d7bf907ca2" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019bea1c-d31a-7fd6-9136-48d7bf907ca2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019bea1c-d31a-782a-b9ed-802adad47840" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019bea1c-d31a-7fd6-9136-48d7bf907ca2" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019bea1c-d31a-782a-b9ed-802adad47840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrencyRiskMember_019bea1c-d31a-7f9a-879c-cb8e3881c956" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrencyRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfRisksDomain_019bea1c-d31a-782a-b9ed-802adad47840" xlink:to="loc_ifrs-full_CurrencyRiskMember_019bea1c-d31a-7f9a-879c-cb8e3881c956" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInRiskVariableAxis_019bfd87-29dd-7f16-8d60-d996d7ef7768" xlink:href="tlx-20251231.xsd#tlx_ChangeInRiskVariableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureTable_019bea1c-d319-7930-aa5e-d02b1693bda2" xlink:to="loc_tlx_ChangeInRiskVariableAxis_019bfd87-29dd-7f16-8d60-d996d7ef7768" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7f16-8d60-d996d7ef7768_default" xlink:href="tlx-20251231.xsd#tlx_ChangeInRiskVariableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tlx_ChangeInRiskVariableAxis_019bfd87-29dd-7f16-8d60-d996d7ef7768" xlink:to="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7f16-8d60-d996d7ef7768_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7527-9420-3c307e1e3674" xlink:href="tlx-20251231.xsd#tlx_ChangeInRiskVariableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tlx_ChangeInRiskVariableAxis_019bfd87-29dd-7f16-8d60-d996d7ef7768" xlink:to="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7527-9420-3c307e1e3674" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TenPercentIncreaseMember_019bea1c-d31a-7dcb-8c7e-9b94c283dc14" xlink:href="tlx-20251231.xsd#tlx_TenPercentIncreaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7527-9420-3c307e1e3674" xlink:to="loc_tlx_TenPercentIncreaseMember_019bea1c-d31a-7dcb-8c7e-9b94c283dc14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TenPercentDecreaseMember_019bea1c-d31a-7b50-960e-9eb6bf873152" xlink:href="tlx-20251231.xsd#tlx_TenPercentDecreaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_ChangeInRiskVariableDomain_019bfd87-29dd-7527-9420-3c307e1e3674" xlink:to="loc_tlx_TenPercentDecreaseMember_019bea1c-d31a-7b50-960e-9eb6bf873152" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariablePercent_019c67b3-3a98-7a2d-a453-2139a24313d9" xlink:href="tlx-20251231.xsd#tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariablePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureLineItems_019bea1c-d31a-76f7-99ff-2a459123ec64" xlink:to="loc_tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariablePercent_019c67b3-3a98-7a2d-a453-2139a24313d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariableImpactOnPreTaxEarnings_019bea1c-d31a-7fef-b8ab-150b719046a9" xlink:href="tlx-20251231.xsd#tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariableImpactOnPreTaxEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureLineItems_019bea1c-d31a-76f7-99ff-2a459123ec64" xlink:to="loc_tlx_SensitivityAnalysisForTypesOfMarketRiskReasonablyPossibleChangeInRiskVariableImpactOnPreTaxEarnings_019bea1c-d31a-7fef-b8ab-150b719046a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RiskExposureAssociatedWithInstrumentsSharingCharacteristic_019bea1c-d31a-780a-9c27-8353b3cb1c86" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RiskExposureAssociatedWithInstrumentsSharingCharacteristic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfCreditRiskExposureLineItems_019bea1c-d31a-76f7-99ff-2a459123ec64" xlink:to="loc_ifrs-full_RiskExposureAssociatedWithInstrumentsSharingCharacteristic_019bea1c-d31a-780a-9c27-8353b3cb1c86" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialriskmanagementCreditRiskDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialriskmanagementCreditRiskDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialriskmanagementCreditRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7c31-a336-ab6cc0054af8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7c31-a336-ab6cc0054af8" xlink:to="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-7c4e-8177-7974a80d3f8b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:to="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-7c4e-8177-7974a80d3f8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-7c4e-8177-7974a80d3f8b_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-7c4e-8177-7974a80d3f8b" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-7c4e-8177-7974a80d3f8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-784a-8b58-079e8ed744b1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TypesOfRisksDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_TypesOfRisksAxis_019b0124-055d-7c4e-8177-7974a80d3f8b" xlink:to="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-784a-8b58-079e8ed744b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CreditRiskMember_019b0124-055d-7714-b26f-103bc75caf3a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CreditRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_TypesOfRisksDomain_019b0124-055d-784a-8b58-079e8ed744b1" xlink:to="loc_ifrs-full_CreditRiskMember_019b0124-055d-7714-b26f-103bc75caf3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PastDueStatusAxis_019b0124-055d-7849-b321-9cdffd3ab0ae" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PastDueStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:to="loc_ifrs-full_PastDueStatusAxis_019b0124-055d-7849-b321-9cdffd3ab0ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-7849-b321-9cdffd3ab0ae_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PastDueStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_PastDueStatusAxis_019b0124-055d-7849-b321-9cdffd3ab0ae" xlink:to="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-7849-b321-9cdffd3ab0ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PastDueStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_PastDueStatusAxis_019b0124-055d-7849-b321-9cdffd3ab0ae" xlink:to="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentMember_019b0124-055d-74e1-9ebe-2728668ef6ce" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:to="loc_ifrs-full_CurrentMember_019b0124-055d-74e1-9ebe-2728668ef6ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanOneMonthAndNotLaterThanTwoMonthsMember_019b0124-055d-7323-af8d-930c00e09600" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanOneMonthAndNotLaterThanTwoMonthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:to="loc_ifrs-full_LaterThanOneMonthAndNotLaterThanTwoMonthsMember_019b0124-055d-7323-af8d-930c00e09600" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanTwoMonthsAndNotLaterThanThreeMonthsMember_019b0124-055d-7b49-9831-5bdfb8a93ed4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanTwoMonthsAndNotLaterThanThreeMonthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:to="loc_ifrs-full_LaterThanTwoMonthsAndNotLaterThanThreeMonthsMember_019b0124-055d-7b49-9831-5bdfb8a93ed4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanThreeMonthsAndNotLaterThanFourMonthsMember_019b0124-055d-7fa7-b8f0-518d42028919" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanThreeMonthsAndNotLaterThanFourMonthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:to="loc_ifrs-full_LaterThanThreeMonthsAndNotLaterThanFourMonthsMember_019b0124-055d-7fa7-b8f0-518d42028919" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanFourMonthsMember_019b0124-055d-7b22-af5e-68852b778e87" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanFourMonthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_PastDueStatusDomain_019b0124-055d-77b6-bc55-1626c42739e1" xlink:to="loc_ifrs-full_LaterThanFourMonthsMember_019b0124-055d-7b22-af5e-68852b778e87" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9db-9d54-709c-8c5b-c2754a244c71" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:to="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9db-9d54-709c-8c5b-c2754a244c71" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-709c-8c5b-c2754a244c71_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9db-9d54-709c-8c5b-c2754a244c71" xlink:to="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-709c-8c5b-c2754a244c71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-7474-93e2-bec368a2859c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis_019be9db-9d54-709c-8c5b-c2754a244c71" xlink:to="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-7474-93e2-bec368a2859c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AccumulatedImpairmentMember_019be9db-d3c6-77fb-b802-8bd8126d235e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AccumulatedImpairmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-7474-93e2-bec368a2859c" xlink:to="loc_ifrs-full_AccumulatedImpairmentMember_019be9db-d3c6-77fb-b802-8bd8126d235e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossCarryingAmountMember_019bfd8a-dc23-7edb-98a4-fe4699861f1b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossCarryingAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CarryingAmountMember_019be9db-9d54-7474-93e2-bec368a2859c" xlink:to="loc_ifrs-full_GrossCarryingAmountMember_019bfd8a-dc23-7edb-98a4-fe4699861f1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9dc-2f27-7b70-a0e8-93fc0a4d8956" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable_019b0124-055d-75f0-9159-a74aa26b3cc2" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9dc-2f27-7b70-a0e8-93fc0a4d8956" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9dc-2f27-7b70-a0e8-93fc0a4d8956_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9dc-2f27-7b70-a0e8-93fc0a4d8956" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9dc-2f27-7b70-a0e8-93fc0a4d8956_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9dc-2f27-73a7-ad12-c09d44100fa1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsAxis_019be9dc-2f27-7b70-a0e8-93fc0a4d8956" xlink:to="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9dc-2f27-73a7-ad12-c09d44100fa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeReceivablesMember_019be9dc-4a86-73b9-95cf-ca9b7addd091" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_ClassesOfFinancialInstrumentsDomain_019be9dc-2f27-73a7-ad12-c09d44100fa1" xlink:to="loc_ifrs-full_TradeReceivablesMember_019be9dc-4a86-73b9-95cf-ca9b7addd091" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialAssets_019b0124-055d-7fb8-9273-3ada62f6b248" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems_019b0124-055d-7c31-a336-ab6cc0054af8" xlink:to="loc_ifrs-full_FinancialAssets_019b0124-055d-7fb8-9273-3ada62f6b248" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/FinancialriskmanagementRemainingContractualMaturitiesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#FinancialriskmanagementRemainingContractualMaturitiesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/FinancialriskmanagementRemainingContractualMaturitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesLineItems_019b0124-055d-724c-863a-6ed4196a7843" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesTable_019b0124-055d-7e20-9f51-8dabe1fc9e3d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesLineItems_019b0124-055d-724c-863a-6ed4196a7843" xlink:to="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesTable_019b0124-055d-7e20-9f51-8dabe1fc9e3d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityAxis_019b0124-055d-7b66-8f41-085da8b35228" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesTable_019b0124-055d-7e20-9f51-8dabe1fc9e3d" xlink:to="loc_ifrs-full_MaturityAxis_019b0124-055d-7b66-8f41-085da8b35228" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityDomain_019b0124-055d-7b66-8f41-085da8b35228_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_MaturityAxis_019b0124-055d-7b66-8f41-085da8b35228" xlink:to="loc_ifrs-full_MaturityDomain_019b0124-055d-7b66-8f41-085da8b35228_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_MaturityAxis_019b0124-055d-7b66-8f41-085da8b35228" xlink:to="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanOneMonthAndNotLaterThanSixMonthsMember_019b0124-055d-79de-967b-1d32bf49fe2e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanOneMonthAndNotLaterThanSixMonthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:to="loc_ifrs-full_LaterThanOneMonthAndNotLaterThanSixMonthsMember_019b0124-055d-79de-967b-1d32bf49fe2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanSixMonthsAndNotLaterThanOneYearMember_019b0124-055d-7734-85d5-65206ed717b0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanSixMonthsAndNotLaterThanOneYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:to="loc_ifrs-full_LaterThanSixMonthsAndNotLaterThanOneYearMember_019b0124-055d-7734-85d5-65206ed717b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanOneYearAndNotLaterThanFiveYearsMember_019b0124-055d-7173-8393-e8277b21d4bb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanOneYearAndNotLaterThanFiveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:to="loc_ifrs-full_LaterThanOneYearAndNotLaterThanFiveYearsMember_019b0124-055d-7173-8393-e8277b21d4bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanFiveYearsMember_019b0124-055d-7e07-91d0-1d43db793e00" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanFiveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7fbb-a79c-9be1a8aa03ef" xlink:to="loc_ifrs-full_LaterThanFiveYearsMember_019b0124-055d-7e07-91d0-1d43db793e00" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesLineItems_019b0124-055d-724c-863a-6ed4196a7843" xlink:to="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherPayablesUndiscountedCashFlows_019b0124-055d-7a32-8bc9-ccc06d9098cd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherPayablesUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_TradeAndOtherPayablesUndiscountedCashFlows_019b0124-055d-7a32-8bc9-ccc06d9098cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherCurrentPayables_019be111-301a-748e-8629-1fdabe9dfc9c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentPayables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_TradeAndOtherCurrentPayables_019be111-301a-748e-8629-1fdabe9dfc9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherNonCurrentLiabilitiesUndiscountedCashFlows_019c5e6c-6368-7e92-90f0-5e76fe2fad67" xlink:href="tlx-20251231.xsd#tlx_OtherNonCurrentLiabilitiesUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_tlx_OtherNonCurrentLiabilitiesUndiscountedCashFlows_019c5e6c-6368-7e92-90f0-5e76fe2fad67" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherNoncurrentLiabilities_019c56dd-df47-79f1-bb51-081cb87b40bc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_OtherNoncurrentLiabilities_019c56dd-df47-79f1-bb51-081cb87b40bc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_BankBorrowingsUndiscountedCashFlows_019be112-574c-7181-a28d-110cfc13eaf2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_BankBorrowingsUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_BankBorrowingsUndiscountedCashFlows_019be112-574c-7181-a28d-110cfc13eaf2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Borrowings_019b0124-055d-7eb7-aa53-fda405e4deac" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_Borrowings_019b0124-055d-7eb7-aa53-fda405e4deac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossLeaseLiabilities_019be112-e020-7341-8e96-d4cf68ae4de6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_GrossLeaseLiabilities_019be112-e020-7341-8e96-d4cf68ae4de6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LeaseLiabilities_019b0124-055d-72cc-a7f8-86cf828ad6d3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_LeaseLiabilities_019b0124-055d-72cc-a7f8-86cf828ad6d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_GovernmentGrantLiabilityUndiscountedCashFlows_019be113-e5a9-7d3b-90a5-7721d1e013e6" xlink:href="tlx-20251231.xsd#tlx_GovernmentGrantLiabilityUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_tlx_GovernmentGrantLiabilityUndiscountedCashFlows_019be113-e5a9-7d3b-90a5-7721d1e013e6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GovernmentGrants_019b0124-055d-7fa5-811f-582f821f7b9b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GovernmentGrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_GovernmentGrants_019b0124-055d-7fa5-811f-582f821f7b9b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentConsiderationLiabilityUndiscountedCashFlows_019be115-cf8d-7b4b-acea-e31099411ad3" xlink:href="tlx-20251231.xsd#tlx_ContingentConsiderationLiabilityUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_tlx_ContingentConsiderationLiabilityUndiscountedCashFlows_019be115-cf8d-7b4b-acea-e31099411ad3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ContingentConsideration_019b0124-055d-737c-87f3-db3fd164bc6a" xlink:href="tlx-20251231.xsd#tlx_ContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_tlx_ContingentConsideration_019b0124-055d-737c-87f3-db3fd164bc6a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NonderivativeFinancialLiabilitiesUndiscountedCashFlows_019b0124-055d-7b92-a9d7-ed9da385cd95" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NonderivativeFinancialLiabilitiesUndiscountedCashFlows"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_NonderivativeFinancialLiabilitiesUndiscountedCashFlows_019b0124-055d-7b92-a9d7-ed9da385cd95" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinancialLiabilities_019b0124-055d-7f3a-8d86-3dee5d79cc1f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract_019b0124-055d-7367-b5a6-2ad53aa1b9f3" xlink:to="loc_ifrs-full_FinancialLiabilities_019b0124-055d-7f3a-8d86-3dee5d79cc1f" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/CommitmentsDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#CommitmentsDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/CommitmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CommitmentsAndContingenciesLineItems_019b0124-055d-7881-ae4b-20495c6be25b" xlink:href="tlx-20251231.xsd#tlx_CommitmentsAndContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CommitmentsAndContingenciesTable_019b0124-055d-794f-8998-8c983781b3db" xlink:href="tlx-20251231.xsd#tlx_CommitmentsAndContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tlx_CommitmentsAndContingenciesLineItems_019b0124-055d-7881-ae4b-20495c6be25b" xlink:to="loc_tlx_CommitmentsAndContingenciesTable_019b0124-055d-794f-8998-8c983781b3db" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityAxis_019b0124-055d-773b-b8c6-56124216ecd1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tlx_CommitmentsAndContingenciesTable_019b0124-055d-794f-8998-8c983781b3db" xlink:to="loc_ifrs-full_MaturityAxis_019b0124-055d-773b-b8c6-56124216ecd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityDomain_019b0124-055d-773b-b8c6-56124216ecd1_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_MaturityAxis_019b0124-055d-773b-b8c6-56124216ecd1" xlink:to="loc_ifrs-full_MaturityDomain_019b0124-055d-773b-b8c6-56124216ecd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_MaturityDomain_019b0124-055d-7d8f-9e41-1e56e92dedc2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_MaturityAxis_019b0124-055d-773b-b8c6-56124216ecd1" xlink:to="loc_ifrs-full_MaturityDomain_019b0124-055d-7d8f-9e41-1e56e92dedc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NotLaterThanOneYearMember_019b0124-055d-7663-a196-95a3091eb9d3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NotLaterThanOneYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7d8f-9e41-1e56e92dedc2" xlink:to="loc_ifrs-full_NotLaterThanOneYearMember_019b0124-055d-7663-a196-95a3091eb9d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LaterThanOneYearMember_019b0124-055d-7dd0-9691-bb7f229ed088" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LaterThanOneYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_MaturityDomain_019b0124-055d-7d8f-9e41-1e56e92dedc2" xlink:to="loc_ifrs-full_LaterThanOneYearMember_019b0124-055d-7dd0-9691-bb7f229ed088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CapitalCommitmentsAbstract_019b0124-055d-7ce8-8f82-15d08c3ad10c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CapitalCommitmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tlx_CommitmentsAndContingenciesLineItems_019b0124-055d-7881-ae4b-20495c6be25b" xlink:to="loc_ifrs-full_CapitalCommitmentsAbstract_019b0124-055d-7ce8-8f82-15d08c3ad10c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ContractualCapitalCommitments_019b0124-055d-7215-89df-af513a3f136a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ContractualCapitalCommitments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CapitalCommitmentsAbstract_019b0124-055d-7ce8-8f82-15d08c3ad10c" xlink:to="loc_ifrs-full_ContractualCapitalCommitments_019b0124-055d-7215-89df-af513a3f136a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ResearchAndDevelopmentsCommitmentsContractualObligations_019c2211-836d-74e8-b928-d0984bd23521" xlink:href="tlx-20251231.xsd#tlx_ResearchAndDevelopmentsCommitmentsContractualObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CapitalCommitmentsAbstract_019b0124-055d-7ce8-8f82-15d08c3ad10c" xlink:to="loc_tlx_ResearchAndDevelopmentsCommitmentsContractualObligations_019c2211-836d-74e8-b928-d0984bd23521" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CapitalCommitments_019c2212-2fe6-7316-9dcc-41d10c9bfa76" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CapitalCommitments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CapitalCommitmentsAbstract_019b0124-055d-7ce8-8f82-15d08c3ad10c" xlink:to="loc_ifrs-full_CapitalCommitments_019c2212-2fe6-7316-9dcc-41d10c9bfa76" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RelatedpartytransactionsNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RelatedpartytransactionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RelatedpartytransactionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019be103-5208-7576-bac0-bf3d924241c0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019be103-5208-7834-819c-98bb7d15fe4f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019be103-5208-7576-bac0-bf3d924241c0" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019be103-5208-7834-819c-98bb7d15fe4f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesAxis_019be103-5208-7fb3-b56e-360a1ebc455d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019be103-5208-7834-819c-98bb7d15fe4f" xlink:to="loc_ifrs-full_SeparateManagementEntitiesAxis_019be103-5208-7fb3-b56e-360a1ebc455d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesDomain_019be103-5208-7fb3-b56e-360a1ebc455d_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SeparateManagementEntitiesAxis_019be103-5208-7fb3-b56e-360a1ebc455d" xlink:to="loc_ifrs-full_SeparateManagementEntitiesDomain_019be103-5208-7fb3-b56e-360a1ebc455d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesDomain_019be103-5208-734f-8352-cd89422363f8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SeparateManagementEntitiesAxis_019be103-5208-7fb3-b56e-360a1ebc455d" xlink:to="loc_ifrs-full_SeparateManagementEntitiesDomain_019be103-5208-734f-8352-cd89422363f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ABXCROMember_019be103-5208-788c-92a1-f1e3fe02705f" xlink:href="tlx-20251231.xsd#tlx_ABXCROMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SeparateManagementEntitiesDomain_019be103-5208-734f-8352-cd89422363f8" xlink:to="loc_tlx_ABXCROMember_019be103-5208-788c-92a1-f1e3fe02705f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_UpfrontCashConsideration_019be103-5208-7d06-8b44-47b182a52438" xlink:href="tlx-20251231.xsd#tlx_UpfrontCashConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019be103-5208-7576-bac0-bf3d924241c0" xlink:to="loc_tlx_UpfrontCashConsideration_019be103-5208-7d06-8b44-47b182a52438" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_BusinessAcquisitionConsiderationTerm_019be103-5208-7041-992d-88b290dfb7d4" xlink:href="tlx-20251231.xsd#tlx_BusinessAcquisitionConsiderationTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019be103-5208-7576-bac0-bf3d924241c0" xlink:to="loc_tlx_BusinessAcquisitionConsiderationTerm_019be103-5208-7041-992d-88b290dfb7d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AmountIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntity_019be103-5208-7db4-8fdc-3c0f68fd6e6a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AmountIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019be103-5208-7576-bac0-bf3d924241c0" xlink:to="loc_ifrs-full_AmountIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntity_019be103-5208-7db4-8fdc-3c0f68fd6e6a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RelatedpartytransactionsScheduleofPrincipalSubsidiariesDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RelatedpartytransactionsScheduleofPrincipalSubsidiariesDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RelatedpartytransactionsScheduleofPrincipalSubsidiariesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b0124-055d-7cb6-a773-ad4541a37716" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b0124-055d-73ee-a2a6-55e7a290315d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b0124-055d-7cb6-a773-ad4541a37716" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b0124-055d-73ee-a2a6-55e7a290315d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInSubsidiariesAxis_019b0124-055d-7b41-a35d-50d191286dde" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b0124-055d-73ee-a2a6-55e7a290315d" xlink:to="loc_ifrs-full_SignificantInvestmentsInSubsidiariesAxis_019b0124-055d-7b41-a35d-50d191286dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7b41-a35d-50d191286dde_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesAxis_019b0124-055d-7b41-a35d-50d191286dde" xlink:to="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7b41-a35d-50d191286dde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesAxis_019b0124-055d-7b41-a35d-50d191286dde" xlink:to="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsInnovationsPtyLtdMember_019b0124-055d-7834-a1d8-9be104250d49" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsInnovationsPtyLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsInnovationsPtyLtdMember_019b0124-055d-7834-a1d8-9be104250d49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsHoldingsPtyLimitedMember_019b0124-055d-76b4-b089-8da20c23ab21" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsHoldingsPtyLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsHoldingsPtyLimitedMember_019b0124-055d-76b4-b089-8da20c23ab21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsInternationalHoldingsPtyLimitedMember_019b0124-055d-7f68-893a-77d7b2dfed01" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsInternationalHoldingsPtyLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsInternationalHoldingsPtyLimitedMember_019b0124-055d-7f68-893a-77d7b2dfed01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsAustraliaHoldingsPtyLimitedMember_019b0124-055d-7ed0-8efa-054572016b97" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsAustraliaHoldingsPtyLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsAustraliaHoldingsPtyLimitedMember_019b0124-055d-7ed0-8efa-054572016b97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsANZPtyLtdMember_019b0124-055d-7be0-a19d-207fd9133a71" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsANZPtyLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsANZPtyLtdMember_019b0124-055d-7be0-a19d-207fd9133a71" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsCorporatePtyLimitedMember_019b0124-055d-766a-9c1a-71a5e9baaebd" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsCorporatePtyLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsCorporatePtyLimitedMember_019b0124-055d-766a-9c1a-71a5e9baaebd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsBelgiumSRLMember_019b0124-055d-7067-bfec-89cd7e7755fb" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsBelgiumSRLMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsBelgiumSRLMember_019b0124-055d-7067-bfec-89cd7e7755fb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixInnovationsSAMember_019b0124-055d-7692-9c89-aa49d362e0a9" xlink:href="tlx-20251231.xsd#tlx_TelixInnovationsSAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixInnovationsSAMember_019b0124-055d-7692-9c89-aa49d362e0a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixInnovationsRphParticipacoesLtdMember_019b0124-055d-745a-815d-518b3a1f5597" xlink:href="tlx-20251231.xsd#tlx_TelixInnovationsRphParticipacoesLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixInnovationsRphParticipacoesLtdMember_019b0124-055d-745a-815d-518b3a1f5597" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsCanadaIncMember_019b0124-055d-7957-836d-f1db0028daa7" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsCanadaIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsCanadaIncMember_019b0124-055d-7957-836d-f1db0028daa7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixARTMSIncMember_019b0124-055d-7a37-b72f-af94db9d0c5f" xlink:href="tlx-20251231.xsd#tlx_TelixARTMSIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixARTMSIncMember_019b0124-055d-7a37-b72f-af94db9d0c5f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsFranceSASMember_019b0124-055d-7bb3-9a27-3918b16049e7" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsFranceSASMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsFranceSASMember_019b0124-055d-7bb3-9a27-3918b16049e7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsGermanyGmbHMember_019b0124-055d-734e-a9b1-d79d9acbda8a" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsGermanyGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsGermanyGmbHMember_019b0124-055d-734e-a9b1-d79d9acbda8a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RhinePharmaGmbHFormerlyTelixPharmaceuticalsGermanyGmbHMember_019b0124-055d-72ba-91f7-0fc0b5345484" xlink:href="tlx-20251231.xsd#tlx_RhinePharmaGmbHFormerlyTelixPharmaceuticalsGermanyGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_RhinePharmaGmbHFormerlyTelixPharmaceuticalsGermanyGmbHMember_019b0124-055d-72ba-91f7-0fc0b5345484" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeiaGmbHCoKGMember_019b0124-055d-7d39-9a8b-32bf631f0bbe" xlink:href="tlx-20251231.xsd#tlx_TherapeiaGmbHCoKGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TherapeiaGmbHCoKGMember_019b0124-055d-7d39-9a8b-32bf631f0bbe" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TherapeiaVerwaltungsGmbHMember_019b0124-055d-763c-b858-8ec006020671" xlink:href="tlx-20251231.xsd#tlx_TherapeiaVerwaltungsGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TherapeiaVerwaltungsGmbHMember_019b0124-055d-763c-b858-8ec006020671" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaJapanKKMember_019c5521-7960-74ce-95d9-14532238cbd4" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaJapanKKMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaJapanKKMember_019c5521-7960-74ce-95d9-14532238cbd4" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsNZLimitedMember_019b0124-055d-7f8b-9827-cd500738e0aa" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsNZLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsNZLimitedMember_019b0124-055d-7f8b-9827-cd500738e0aa" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsSingaporePteLtdMember_019b0124-055d-75c4-a0ed-82adbb0fc323" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsSingaporePteLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsSingaporePteLtdMember_019b0124-055d-75c4-a0ed-82adbb0fc323" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsSwitzerlandGmbHMember_019b0124-055d-73b6-a637-c9469215ff8d" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsSwitzerlandGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsSwitzerlandGmbHMember_019b0124-055d-73b6-a637-c9469215ff8d" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsUKLtdMember_019b0124-055d-7018-930b-f2babf5a2413" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsUKLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsUKLtdMember_019b0124-055d-7018-930b-f2babf5a2413" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LightpointSurgicalLtdMember_019b0124-055d-7441-9d3c-8fa76e0d78f6" xlink:href="tlx-20251231.xsd#tlx_LightpointSurgicalLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_LightpointSurgicalLtdMember_019b0124-055d-7441-9d3c-8fa76e0d78f6" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LightpointSurgicalSpainS.L.LightpointMedicalEspanaSLUMember_019b0124-055d-7baf-bd08-cc63358a6b07" xlink:href="tlx-20251231.xsd#tlx_LightpointSurgicalSpainS.L.LightpointMedicalEspanaSLUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_LightpointSurgicalSpainS.L.LightpointMedicalEspanaSLUMember_019b0124-055d-7baf-bd08-cc63358a6b07" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixPharmaceuticalsUSIncMember_019b0124-055d-7698-b3e9-26647a362916" xlink:href="tlx-20251231.xsd#tlx_TelixPharmaceuticalsUSIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixPharmaceuticalsUSIncMember_019b0124-055d-7698-b3e9-26647a362916" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixOptimalTracersLLCMember_019b0124-055d-7600-a1de-2328abe3559d" xlink:href="tlx-20251231.xsd#tlx_TelixOptimalTracersLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixOptimalTracersLLCMember_019b0124-055d-7600-a1de-2328abe3559d" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixIsoTherapeuticsGroupIncMember_019b0124-055d-7a2f-a33d-3683953e907b" xlink:href="tlx-20251231.xsd#tlx_TelixIsoTherapeuticsGroupIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixIsoTherapeuticsGroupIncMember_019b0124-055d-7a2f-a33d-3683953e907b" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixQSAMIncMember_019b0124-055d-7a63-a4dc-4c7f5370e662" xlink:href="tlx-20251231.xsd#tlx_TelixQSAMIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixQSAMIncMember_019b0124-055d-7a63-a4dc-4c7f5370e662" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_QSAMTherapeuticsIncMember_019b0124-055d-7d4c-a98e-d9f5dc16d61a" xlink:href="tlx-20251231.xsd#tlx_QSAMTherapeuticsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_QSAMTherapeuticsIncMember_019b0124-055d-7d4c-a98e-d9f5dc16d61a" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_RLSUSAIncMember_019c4c25-ccf5-7989-8169-8956b6124b3e" xlink:href="tlx-20251231.xsd#tlx_RLSUSAIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_RLSUSAIncMember_019c4c25-ccf5-7989-8169-8956b6124b3e" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_LasVegasRadiopharmacyInc.Member_019c4c26-1038-76b9-88d0-8eb456f2638d" xlink:href="tlx-20251231.xsd#tlx_LasVegasRadiopharmacyInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_LasVegasRadiopharmacyInc.Member_019c4c26-1038-76b9-88d0-8eb456f2638d" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_TelixTargetingTechnologiesInc.Member_019c4467-9f78-7bdd-b78a-fae5bc2787b7" xlink:href="tlx-20251231.xsd#tlx_TelixTargetingTechnologiesInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_TelixTargetingTechnologiesInc.Member_019c4467-9f78-7bdd-b78a-fae5bc2787b7" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ARTMSUSIncMember_019b0124-055d-7925-a09e-de46128abec9" xlink:href="tlx-20251231.xsd#tlx_ARTMSUSIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SignificantInvestmentsInSubsidiariesDomain_019b0124-055d-7a28-9812-e56c41d4baa8" xlink:to="loc_tlx_ARTMSUSIncMember_019b0124-055d-7925-a09e-de46128abec9" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasAxis_019be0fd-cad6-7be7-b324-a82f2e957dca" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b0124-055d-73ee-a2a6-55e7a290315d" xlink:to="loc_ifrs-full_GeographicalAreasAxis_019be0fd-cad6-7be7-b324-a82f2e957dca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7be7-b324-a82f2e957dca_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019be0fd-cad6-7be7-b324-a82f2e957dca" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7be7-b324-a82f2e957dca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeographicalAreasDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_GeographicalAreasAxis_019be0fd-cad6-7be7-b324-a82f2e957dca" xlink:to="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_AU_019be0fd-cad6-7f9e-bbf4-921669deb9cc" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_AU"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_AU_019be0fd-cad6-7f9e-bbf4-921669deb9cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BE_019be0fd-cad6-7227-93a1-41c3142c4d09" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_BE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_BE_019be0fd-cad6-7227-93a1-41c3142c4d09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BR_019be0fd-cad6-732a-9748-0173bde4d01a" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_BR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_BR_019be0fd-cad6-732a-9748-0173bde4d01a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_019be0fd-cad6-77dd-8d17-c439cb907a01" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_CA_019be0fd-cad6-77dd-8d17-c439cb907a01" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_FR_019be0fd-cad6-76ae-afb4-309f92de5e28" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_FR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_FR_019be0fd-cad6-76ae-afb4-309f92de5e28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_DE_019be0fd-cad6-7f91-8afe-a33eea0604a9" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_DE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_DE_019be0fd-cad6-7f91-8afe-a33eea0604a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_JP_019c5522-2588-7e66-8ef0-b1e0582fe442" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_JP"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_JP_019c5522-2588-7e66-8ef0-b1e0582fe442" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_NZ_019be0fd-cad6-7f5a-a309-27bfd3d85c70" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_NZ"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_NZ_019be0fd-cad6-7f5a-a309-27bfd3d85c70" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SG_019be0fd-cad6-7aa3-925e-63f3bb1b2e75" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_SG"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_SG_019be0fd-cad6-7aa3-925e-63f3bb1b2e75" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CH_019be0fd-cad6-77d6-adfc-7999773ecd52" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_CH_019be0fd-cad6-77d6-adfc-7999773ecd52" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_019be0fd-cad6-720e-8ae9-ca6f0f7ffa89" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_GB_019be0fd-cad6-720e-8ae9-ca6f0f7ffa89" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_ES_019be0fd-cad6-7ac8-b7f4-304bf389c779" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_ES"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_ES_019be0fd-cad6-7ac8-b7f4-304bf389c779" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019be0fd-cad6-7566-8117-c30ce472165c" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_GeographicalAreasDomain_019be0fd-cad6-7678-aa52-a52284327265" xlink:to="loc_country_US_019be0fd-cad6-7566-8117-c30ce472165c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProportionOfOwnershipInterestInSubsidiary_019b0124-055d-7193-89be-d22bab4e86ed" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProportionOfOwnershipInterestInSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b0124-055d-7cb6-a773-ad4541a37716" xlink:to="loc_ifrs-full_ProportionOfOwnershipInterestInSubsidiary_019b0124-055d-7193-89be-d22bab4e86ed" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/RemunerationofauditorDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#RemunerationofauditorDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/RemunerationofauditorDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesTable_019b0124-055d-74be-bbbe-733fad1427ab" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:to="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesTable_019b0124-055d-74be-bbbe-733fad1427ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesAxis_019b0124-055d-7833-b9ae-ebf67d08cae9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesTable_019b0124-055d-74be-bbbe-733fad1427ab" xlink:to="loc_ifrs-full_SeparateManagementEntitiesAxis_019b0124-055d-7833-b9ae-ebf67d08cae9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-7833-b9ae-ebf67d08cae9_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_SeparateManagementEntitiesAxis_019b0124-055d-7833-b9ae-ebf67d08cae9" xlink:to="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-7833-b9ae-ebf67d08cae9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-746f-b312-cf4be47a7f72" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SeparateManagementEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_SeparateManagementEntitiesAxis_019b0124-055d-7833-b9ae-ebf67d08cae9" xlink:to="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-746f-b312-cf4be47a7f72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_PricewaterhouseCoopersAustraliaAndRelatedNetworkFirmsMember_019b0124-055d-7324-925d-172d875ca051" xlink:href="tlx-20251231.xsd#tlx_PricewaterhouseCoopersAustraliaAndRelatedNetworkFirmsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-746f-b312-cf4be47a7f72" xlink:to="loc_tlx_PricewaterhouseCoopersAustraliaAndRelatedNetworkFirmsMember_019b0124-055d-7324-925d-172d875ca051" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_OtherAuditorsAndTheirRelatedNetworkFirmsMember_019b0124-055d-7a50-b89c-c09191411790" xlink:href="tlx-20251231.xsd#tlx_OtherAuditorsAndTheirRelatedNetworkFirmsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_SeparateManagementEntitiesDomain_019b0124-055d-746f-b312-cf4be47a7f72" xlink:to="loc_tlx_OtherAuditorsAndTheirRelatedNetworkFirmsMember_019b0124-055d-7a50-b89c-c09191411790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AuditorsRemunerationForAuditServices_019b0124-055d-7998-948b-d5ab5be4c451" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AuditorsRemunerationForAuditServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:to="loc_ifrs-full_AuditorsRemunerationForAuditServices_019b0124-055d-7998-948b-d5ab5be4c451" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AuditorsRemunerationForTaxServices_019b0124-055d-7626-afa1-855de18edc7a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AuditorsRemunerationForTaxServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:to="loc_ifrs-full_AuditorsRemunerationForTaxServices_019b0124-055d-7626-afa1-855de18edc7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AuditorsRemunerationForOtherServices_019b0124-055d-7c79-ac31-08700510adf4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AuditorsRemunerationForOtherServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:to="loc_ifrs-full_AuditorsRemunerationForOtherServices_019b0124-055d-7c79-ac31-08700510adf4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AuditorsRemuneration_019b0124-055d-7953-86e1-1c1388d996d1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AuditorsRemuneration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfAmountsIncurredByEntityForProvisionOfKeyManagementPersonnelServicesProvidedBySeparateManagementEntitiesLineItems_019b0124-055d-7943-aea1-e85b09e608b2" xlink:to="loc_ifrs-full_AuditorsRemuneration_019b0124-055d-7953-86e1-1c1388d996d1" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/ParententityfinancialinformationDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#ParententityfinancialinformationDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/ParententityfinancialinformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44ef-f068-7880-be6e-0d8baa776228" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44ef-f068-7880-be6e-0d8baa776228" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44ef-f068-7a52-b538-93a90af93a22" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44ef-f068-7880-be6e-0d8baa776228" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44ef-f068-7a52-b538-93a90af93a22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44ef-f068-7a52-b538-93a90af93a22_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44ef-f068-7a52-b538-93a90af93a22" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44ef-f068-7a52-b538-93a90af93a22_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44ef-f068-7699-8175-915fb28e2604" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44ef-f068-7a52-b538-93a90af93a22" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44ef-f068-7699-8175-915fb28e2604" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ParentMember_019b44ef-f068-7771-b4df-27645646a17f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44ef-f068-7699-8175-915fb28e2604" xlink:to="loc_ifrs-full_ParentMember_019b44ef-f068-7771-b4df-27645646a17f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_AssetsAbstract_019c469a-4e42-7c5c-800f-1ff5f865b862" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_AssetsAbstract_019c469a-4e42-7c5c-800f-1ff5f865b862" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentAssets_019b44ef-f068-7cc3-a7df-1140464df118" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AssetsAbstract_019c469a-4e42-7c5c-800f-1ff5f865b862" xlink:to="loc_ifrs-full_CurrentAssets_019b44ef-f068-7cc3-a7df-1140464df118" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentAssets_019b44ef-f068-7385-945e-046d505c0ceb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AssetsAbstract_019c469a-4e42-7c5c-800f-1ff5f865b862" xlink:to="loc_ifrs-full_NoncurrentAssets_019b44ef-f068-7385-945e-046d505c0ceb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Assets_019b44ef-f068-7b0f-b55b-88acb0baa545" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_AssetsAbstract_019c469a-4e42-7c5c-800f-1ff5f865b862" xlink:to="loc_ifrs-full_Assets_019b44ef-f068-7b0f-b55b-88acb0baa545" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LiabilitiesAbstract_019c469b-3f4f-7698-a75d-ebd166c80dca" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_LiabilitiesAbstract_019c469b-3f4f-7698-a75d-ebd166c80dca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentLiabilities_019b44ef-f068-7926-857b-e31de109d9e0" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesAbstract_019c469b-3f4f-7698-a75d-ebd166c80dca" xlink:to="loc_ifrs-full_CurrentLiabilities_019b44ef-f068-7926-857b-e31de109d9e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentLiabilities_019b44ef-f068-7d62-925b-58ec7011a7ff" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesAbstract_019c469b-3f4f-7698-a75d-ebd166c80dca" xlink:to="loc_ifrs-full_NoncurrentLiabilities_019b44ef-f068-7d62-925b-58ec7011a7ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Liabilities_019b44ef-f068-7fff-9d52-a199f827cd4a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_LiabilitiesAbstract_019c469b-3f4f-7698-a75d-ebd166c80dca" xlink:to="loc_ifrs-full_Liabilities_019b44ef-f068-7fff-9d52-a199f827cd4a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NetAssetsLiabilities_019b44ef-f068-713a-a730-db7612eee9bc" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NetAssetsLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_NetAssetsLiabilities_019b44ef-f068-713a-a730-db7612eee9bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapital_019b44ef-f068-7687-a890-6671216e2380" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:to="loc_ifrs-full_IssuedCapital_019b44ef-f068-7687-a890-6671216e2380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CapitalReserveDeficit_019b44ef-f068-754c-a42d-9e929822937e" xlink:href="tlx-20251231.xsd#tlx_CapitalReserveDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:to="loc_tlx_CapitalReserveDeficit_019b44ef-f068-754c-a42d-9e929822937e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherReserves_019b44ef-f068-7531-a276-7d56c2bb42c8" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:to="loc_ifrs-full_OtherReserves_019b44ef-f068-7531-a276-7d56c2bb42c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RetainedEarnings_019b44ef-f068-7697-8718-03ff7d56aafa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RetainedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:to="loc_ifrs-full_RetainedEarnings_019b44ef-f068-7697-8718-03ff7d56aafa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019b44ef-f068-7121-878d-2c05070ae8a6" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4bbe-ef4c-77b0-b943-b0bec7767bee" xlink:to="loc_ifrs-full_Equity_019b44ef-f068-7121-878d-2c05070ae8a6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_StatementOfComprehensiveIncomeAbstract_019c7461-b22e-79f5-8adf-76b9fcd0facd" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_StatementOfComprehensiveIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44ef-f068-7db9-93eb-dd2fd6feb259" xlink:to="loc_ifrs-full_StatementOfComprehensiveIncomeAbstract_019c7461-b22e-79f5-8adf-76b9fcd0facd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossAttributableToOwnersOfParent_019b44ef-f068-759f-abad-0f2ce7046d71" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossAttributableToOwnersOfParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_StatementOfComprehensiveIncomeAbstract_019c7461-b22e-79f5-8adf-76b9fcd0facd" xlink:to="loc_ifrs-full_ProfitLossAttributableToOwnersOfParent_019b44ef-f068-759f-abad-0f2ce7046d71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComprehensiveIncomeAttributableToOwnersOfParent_019b44ef-f068-7169-aa0d-9cc3f7c30b95" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComprehensiveIncomeAttributableToOwnersOfParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_StatementOfComprehensiveIncomeAbstract_019c7461-b22e-79f5-8adf-76b9fcd0facd" xlink:to="loc_ifrs-full_ComprehensiveIncomeAttributableToOwnersOfParent_019b44ef-f068-7169-aa0d-9cc3f7c30b95" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeedofcrossguaranteeNarrativeDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeedofcrossguaranteeNarrativeDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeedofcrossguaranteeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b4502-14b8-7112-af82-b9fb5c8c9436" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b4502-14b8-7112-af82-b9fb5c8c9436" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b4502-b2b0-74a6-8908-92478004b089" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b4502-14b8-7112-af82-b9fb5c8c9436" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b4502-b2b0-74a6-8908-92478004b089" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b4502-b2b0-74a6-8908-92478004b089_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b4502-b2b0-74a6-8908-92478004b089" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b4502-b2b0-74a6-8908-92478004b089_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b4502-b2b0-723f-8009-af87a696199a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b4502-b2b0-74a6-8908-92478004b089" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b4502-b2b0-723f-8009-af87a696199a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019bea28-b36f-7327-8cec-e6d3a069ee06" xlink:href="tlx-20251231.xsd#tlx_EntitiesPartyToDeedOfCrossGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b4502-b2b0-723f-8009-af87a696199a" xlink:to="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019bea28-b36f-7327-8cec-e6d3a069ee06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLoss_019b4502-b2b0-794a-9b43-95a5acee00ae" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:to="loc_ifrs-full_ProfitLoss_019b4502-b2b0-794a-9b43-95a5acee00ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NetAssetsLiabilities_019b4502-b2b0-705d-bc47-72728f2573b1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NetAssetsLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:to="loc_ifrs-full_NetAssetsLiabilities_019b4502-b2b0-705d-bc47-72728f2573b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashAndCashEquivalents_019b4502-14b8-773a-84d1-9349cbe8cf1d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:to="loc_ifrs-full_CashAndCashEquivalents_019b4502-14b8-773a-84d1-9349cbe8cf1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherCurrentPayablesToRelatedParties_019c4698-59de-7408-9617-4d09de76006d" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentPayablesToRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b4502-14b8-73fb-9609-a9c717236cc4" xlink:to="loc_ifrs-full_TradeAndOtherCurrentPayablesToRelatedParties_019c4698-59de-7408-9617-4d09de76006d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeedofcrossguaranteeScheduleofConsolidatedStatementofComprehensiveIncomeorLossDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeedofcrossguaranteeScheduleofConsolidatedStatementofComprehensiveIncomeorLossDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeedofcrossguaranteeScheduleofConsolidatedStatementofComprehensiveIncomeorLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44fd-dcfb-7b64-9b1a-34db2cebf2aa" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44fd-dcfb-7b64-9b1a-34db2cebf2aa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44fd-dcfb-74fa-8c38-97767392ba6c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019b44fd-dcfb-7b64-9b1a-34db2cebf2aa" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44fd-dcfb-74fa-8c38-97767392ba6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44fd-dcfb-74fa-8c38-97767392ba6c_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44fd-dcfb-74fa-8c38-97767392ba6c" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44fd-dcfb-74fa-8c38-97767392ba6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44fd-dcfb-788c-a6ff-d683a8a36c7f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019b44fd-dcfb-74fa-8c38-97767392ba6c" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44fd-dcfb-788c-a6ff-d683a8a36c7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019b44fd-dcfb-7d1b-ace7-fdb20330c40c" xlink:href="tlx-20251231.xsd#tlx_EntitiesPartyToDeedOfCrossGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019b44fd-dcfb-788c-a6ff-d683a8a36c7f" xlink:to="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019b44fd-dcfb-7d1b-ace7-fdb20330c40c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RevenueFromContractsWithCustomers_019b44fd-dcfb-7d7d-9535-8a6bf8f60d21" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RevenueFromContractsWithCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_RevenueFromContractsWithCustomers_019b44fd-dcfb-7d7d-9535-8a6bf8f60d21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CostOfSales_019b44fd-dcfb-7042-978e-14d44043c557" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CostOfSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_CostOfSales_019b44fd-dcfb-7042-978e-14d44043c557" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GrossProfit_019b44fd-dcfb-793a-b170-9656be1d3c1a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_GrossProfit_019b44fd-dcfb-793a-b170-9656be1d3c1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ResearchAndDevelopmentExpense_019b44fd-dcfb-7732-9a88-1b9b52ac0774" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_ResearchAndDevelopmentExpense_019b44fd-dcfb-7732-9a88-1b9b52ac0774" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_SalesAndMarketingExpense_019b44fd-dcfb-726d-9082-71e89ec5eb87" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_SalesAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_SalesAndMarketingExpense_019b44fd-dcfb-726d-9082-71e89ec5eb87" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_ManufacturingAndDistributionCosts_019b44fd-dcfb-7af1-baa1-b8385e850abe" xlink:href="tlx-20251231.xsd#tlx_ManufacturingAndDistributionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_tlx_ManufacturingAndDistributionCosts_019b44fd-dcfb-7af1-baa1-b8385e850abe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_GeneralAndAdministrativeExpense_019b44fd-dcfb-7437-8b3a-0acbc6ecb49a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_GeneralAndAdministrativeExpense_019b44fd-dcfb-7437-8b3a-0acbc6ecb49a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherGainsLosses_019b44fd-dcfb-79c1-a28f-ce256991c2e9" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_OtherGainsLosses_019b44fd-dcfb-79c1-a28f-ce256991c2e9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossFromOperatingActivities_019b44fd-dcfb-7290-95b4-6e72e3d6c57f" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossFromOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_ProfitLossFromOperatingActivities_019b44fd-dcfb-7290-95b4-6e72e3d6c57f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinanceIncome_019b44fd-dcfb-7a63-96ee-fa4555892b48" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinanceIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_FinanceIncome_019b44fd-dcfb-7a63-96ee-fa4555892b48" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_FinanceCosts_019b44fd-dcfb-7c29-8886-38709f0d2ec3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_FinanceCosts_019b44fd-dcfb-7c29-8886-38709f0d2ec3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLossBeforeTax_019b44fd-dcfb-7918-9245-c73fce08652c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_ProfitLossBeforeTax_019b44fd-dcfb-7918-9245-c73fce08652c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IncomeTaxExpenseContinuingOperations_019b44fd-dcfb-7724-a87b-5a465be87e1e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncomeTaxExpenseContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_IncomeTaxExpenseContinuingOperations_019b44fd-dcfb-7724-a87b-5a465be87e1e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ProfitLoss_019b44fd-dcfb-7c4f-87c1-7d32b7858019" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_ProfitLoss_019b44fd-dcfb-7c4f-87c1-7d32b7858019" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherComprehensiveIncomeNetOfTaxGainsLossesFromInvestmentsInEquityInstruments_019b44fd-dcfb-79b0-b340-318a13eae92a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherComprehensiveIncomeNetOfTaxGainsLossesFromInvestmentsInEquityInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_OtherComprehensiveIncomeNetOfTaxGainsLossesFromInvestmentsInEquityInstruments_019b44fd-dcfb-79b0-b340-318a13eae92a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ComprehensiveIncome_019b44fd-dcfb-7680-9a0a-962a24b14511" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019b44fd-dcfb-7ea8-b9d1-82609b2c73b7" xlink:to="loc_ifrs-full_ComprehensiveIncome_019b44fd-dcfb-7680-9a0a-962a24b14511" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://telixpharma.com/role/DeedofcrossguaranteeConsolidatedStatementofFinancialPositionDetails" xlink:type="simple" xlink:href="tlx-20251231.xsd#DeedofcrossguaranteeConsolidatedStatementofFinancialPositionDetails"/>
  <link:definitionLink xlink:role="http://telixpharma.com/role/DeedofcrossguaranteeConsolidatedStatementofFinancialPositionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019c468b-6205-72f9-8c43-4047faabc03c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019c468b-6205-72f9-8c43-4047faabc03c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019c468b-deb2-7ce5-b4db-f30a5c90c9cf" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable_019c468b-6205-72f9-8c43-4047faabc03c" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019c468b-deb2-7ce5-b4db-f30a5c90c9cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019c468b-deb2-7ce5-b4db-f30a5c90c9cf_default" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019c468b-deb2-7ce5-b4db-f30a5c90c9cf" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019c468b-deb2-7ce5-b4db-f30a5c90c9cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019c468b-deb2-73bd-bdd5-649f5df254a1" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesAxis_019c468b-deb2-7ce5-b4db-f30a5c90c9cf" xlink:to="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019c468b-deb2-73bd-bdd5-649f5df254a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019c468b-deb2-770f-81b7-52e4d451132f" xlink:href="tlx-20251231.xsd#tlx_EntitiesPartyToDeedOfCrossGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CategoriesOfRelatedPartiesDomain_019c468b-deb2-73bd-bdd5-649f5df254a1" xlink:to="loc_tlx_EntitiesPartyToDeedOfCrossGuaranteeMember_019c468b-deb2-770f-81b7-52e4d451132f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CashAndCashEquivalents_019c468b-deb2-723a-af63-f1dad65fe0ac" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:to="loc_ifrs-full_CashAndCashEquivalents_019c468b-deb2-723a-af63-f1dad65fe0ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherCurrentReceivables_019c468b-deb2-71f0-96be-9d7c4ce13f8b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:to="loc_ifrs-full_TradeAndOtherCurrentReceivables_019c468b-deb2-71f0-96be-9d7c4ce13f8b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Inventories_019c468b-deb2-7d84-a79c-6696d2bed6ed" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Inventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:to="loc_ifrs-full_Inventories_019c468b-deb2-7d84-a79c-6696d2bed6ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherCurrentAssets_019c468b-deb2-7b18-89c8-dd51991cbd98" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:to="loc_ifrs-full_OtherCurrentAssets_019c468b-deb2-7b18-89c8-dd51991cbd98" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentAssets_019c468b-deb2-7fef-837d-988cd91e836b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentAssetsAbstract_019c468c-8272-77e4-a974-70b8ec35486e" xlink:to="loc_ifrs-full_CurrentAssets_019c468b-deb2-7fef-837d-988cd91e836b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NetInvestmentInSubsidiaries_019c468b-deb2-7bdb-93c8-bcd723d51841" xlink:href="tlx-20251231.xsd#tlx_NetInvestmentInSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_tlx_NetInvestmentInSubsidiaries_019c468b-deb2-7bdb-93c8-bcd723d51841" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IntangibleAssetsAndGoodwill_019c468b-deb2-735b-98eb-d48de8fe8a60" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_IntangibleAssetsAndGoodwill_019c468b-deb2-735b-98eb-d48de8fe8a60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_PropertyPlantAndEquipment_019c468b-deb2-7f56-8fcd-c9af3cf259fe" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_PropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_PropertyPlantAndEquipment_019c468b-deb2-7f56-8fcd-c9af3cf259fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RightofuseAssets_019c468b-deb2-7b90-8fd2-910cafb665df" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RightofuseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_RightofuseAssets_019c468b-deb2-7b90-8fd2-910cafb665df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentFinancialAssets_019c468b-deb2-7759-83ee-15b0d70fea1e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentFinancialAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_NoncurrentFinancialAssets_019c468b-deb2-7759-83ee-15b0d70fea1e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxAssets_019c468b-deb2-7d54-a742-f4243e5db548" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_DeferredTaxAssets_019c468b-deb2-7d54-a742-f4243e5db548" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherNoncurrentAssets_019c468b-deb2-7f37-a458-6e9cd7a05e9b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_OtherNoncurrentAssets_019c468b-deb2-7f37-a458-6e9cd7a05e9b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentAssets_019c468b-deb2-7e12-b744-dc7fc7957854" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentAssetsAbstract_019c468c-c738-74e8-91e9-62f9cff77291" xlink:to="loc_ifrs-full_NoncurrentAssets_019c468b-deb2-7e12-b744-dc7fc7957854" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Assets_019c468b-deb2-73cf-b32e-ae77332b382a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_Assets_019c468b-deb2-73cf-b32e-ae77332b382a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_TradeAndOtherCurrentPayables_019c468b-deb2-7294-856c-376644ae9da5" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentPayables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_ifrs-full_TradeAndOtherCurrentPayables_019c468b-deb2-7294-856c-376644ae9da5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentContractLiabilities_019c468b-deb2-7d89-88f5-d09bca553c17" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentContractLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_ifrs-full_CurrentContractLiabilities_019c468b-deb2-7d89-88f5-d09bca553c17" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentLeaseLiabilities_019c468b-deb2-7d88-8e52-ca8009583159" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_ifrs-full_CurrentLeaseLiabilities_019c468b-deb2-7d88-8e52-ca8009583159" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_ShorttermBorrowings_019c468b-deb2-76d2-b235-87c78dfcca6b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShorttermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_ifrs-full_ShorttermBorrowings_019c468b-deb2-76d2-b235-87c78dfcca6b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CurrentContingentConsideration_019c468b-deb2-7313-9bbd-eeec276028a6" xlink:href="tlx-20251231.xsd#tlx_CurrentContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_tlx_CurrentContingentConsideration_019c468b-deb2-7313-9bbd-eeec276028a6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CurrentEmployeeBenefitObligations_019c468b-deb2-7549-a410-eecf4be08c87" xlink:href="tlx-20251231.xsd#tlx_CurrentEmployeeBenefitObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_tlx_CurrentEmployeeBenefitObligations_019c468b-deb2-7549-a410-eecf4be08c87" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_CurrentLiabilities_019c468b-deb2-758b-b436-8e158032ed83" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_CurrentLiabilitiesAbstract_019c468e-8522-72b1-aa7a-b9acc4816500" xlink:to="loc_ifrs-full_CurrentLiabilities_019c468b-deb2-758b-b436-8e158032ed83" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentContractLiabilities_019c468f-083d-7ec2-89e2-cc4a03761393" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentContractLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_NoncurrentContractLiabilities_019c468f-083d-7ec2-89e2-cc4a03761393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentLeaseLiabilities_019c468b-deb2-7253-9419-266909d1a22a" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_NoncurrentLeaseLiabilities_019c468b-deb2-7253-9419-266909d1a22a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_LongtermBorrowings_019c468b-deb2-742a-afec-9fed159b1acb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LongtermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_LongtermBorrowings_019c468b-deb2-742a-afec-9fed159b1acb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NonCurrentContingentConsideration_019c468b-deb2-74ae-8d0b-1f01fd104178" xlink:href="tlx-20251231.xsd#tlx_NonCurrentContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_tlx_NonCurrentContingentConsideration_019c468b-deb2-74ae-8d0b-1f01fd104178" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_DeferredTaxLiabilities_019c468b-deb2-732a-9897-69b4b42b495c" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_DeferredTaxLiabilities_019c468b-deb2-732a-9897-69b4b42b495c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_NonCurrentEmployeeBenefitObligations_019c468b-deb2-7bf4-a7e3-292c25218beb" xlink:href="tlx-20251231.xsd#tlx_NonCurrentEmployeeBenefitObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_tlx_NonCurrentEmployeeBenefitObligations_019c468b-deb2-7bf4-a7e3-292c25218beb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NoncurrentLiabilities_019c468b-deb2-7f83-94e2-da425adc90e3" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_NoncurrentLiabilities_019c468b-deb2-7f83-94e2-da425adc90e3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Liabilities_019c468b-deb2-7a06-86af-6da21d05051b" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_NoncurrentLiabilitiesAbstract_019c4690-61b9-7a0f-9a0d-a7ae4a564853" xlink:to="loc_ifrs-full_Liabilities_019c468b-deb2-7a06-86af-6da21d05051b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_NetAssetsLiabilities_019c468b-deb2-7ab0-8b35-da754a010c23" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NetAssetsLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_NetAssetsLiabilities_019c468b-deb2-7ab0-8b35-da754a010c23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesLineItems_019c468b-a6a8-7f7d-94f1-760a984c9db5" xlink:to="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_IssuedCapital_019c468b-deb2-7176-a9cf-3349280e4394" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:to="loc_ifrs-full_IssuedCapital_019c468b-deb2-7176-a9cf-3349280e4394" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tlx_CapitalReserveDeficit_019c468b-deb2-719d-b766-6c54f223ce68" xlink:href="tlx-20251231.xsd#tlx_CapitalReserveDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:to="loc_tlx_CapitalReserveDeficit_019c468b-deb2-719d-b766-6c54f223ce68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_OtherReserves_019c468b-deb2-7051-8fce-6fa0259dafeb" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:to="loc_ifrs-full_OtherReserves_019c468b-deb2-7051-8fce-6fa0259dafeb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_RetainedEarnings_019c468b-deb2-7793-9c8a-ec212b19257e" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RetainedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:to="loc_ifrs-full_RetainedEarnings_019c468b-deb2-7793-9c8a-ec212b19257e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ifrs-full_Equity_019c468b-deb2-7284-8bee-23e400ec9746" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ifrs-full_EquityAbstract_019c4691-ced9-77de-ad80-24aedc491d39" xlink:to="loc_ifrs-full_Equity_019c468b-deb2-7284-8bee-23e400ec9746" xlink:type="arc" order="5"/>
  </link:definitionLink>
</link:linkbase>
