<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by CompSci Transform (tm) - http://www.compsciresources.com -->
<!-- Created: Fri Mar 27 20:02:19 UTC 2026 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#PvpAdjustmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly" roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly"/>
  <roleRef xlink:type="simple" xlink:href="tls-20260507.xsd#tls_r_AdditionalDimensions" roleURI="http://www.telos.com/role/AdditionalDimensions"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="ecd_AllAdjToCompMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllAdjToCompMember"/>
    <loc xlink:type="locator" xlink:label="tls_OneTimeEquityAwardMember" xlink:href="tls-20260507.xsd#tls_OneTimeEquityAwardMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllAdjToCompMember" xlink:to="tls_OneTimeEquityAwardMember" order="5" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <loc xlink:type="locator" xlink:label="tls_MarkGriffinMember" xlink:href="tls-20260507.xsd#tls_MarkGriffinMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllIndividualsMember" xlink:to="tls_MarkGriffinMember" order="2" xbrldt:closed="true"/>
  </definitionLink>
<!-- [WMV6][dHtnuz56ci02IxvV3dKhGgG88YxYyk9BbPYCS5P1ermAnNhgmCnO0UTHjZ2UJRiixGLjbjkl+VK+zCaDzQempnyuql4wAfexubxTavxUJ4SrPxdI5dCsn/K6YfWFhpMdyaVO4tRJpFPCCRVrz7PS6FtEnCyBcvIpjxIcsKVOAz+PnfasKRQ0CkS8UU7wQcmAo+Pzheztwxp6N816mktvB3Qx59w3/CDCO12MlkccgoWzPiwAGK10lDBkZCuPoUTKT/CExsOA1aqGAHIAGMJUl9TvPZz6tDpdXJ6hA4uK1GmZRql6pzj1qWchRuZ5s7Ofr1pwToPHG/J/EFKnDy0/RUuymCKGgVqjbfIyv9p0Clc=] CSR-->
  <definitionLink xlink:role="http://www.telos.com/role/AdditionalDimensions" xlink:type="extended"/>
</linkbase>
