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

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:f9bd63ea-d913-4b2c-a7fc-5d6a04f16bd4,g:a072651b-3ce5-4cb7-8e07-b74e1afca318-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:tls="http://telos.com/20230331" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2020-01-21" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://telos.com/20230331">
  <xs:import namespace="http://fasb.org/srt/2022" schemaLocation="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2022" schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd"/>
  <xs:import namespace="http://www.w3.org/1999/xlink" schemaLocation="http://www.xbrl.org/2003/xlink-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2022" schemaLocation="https://xbrl.sec.gov/dei/2022/dei-2022.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20230331_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20230331_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20230331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20230331_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://telos.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFOPERATIONS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS">
        <link:definition>0000002 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS">
        <link:definition>0000003 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETS" roleURI="http://telos.com/role/CONSOLIDATEDBALANCESHEETS">
        <link:definition>0000004 - Statement - CONSOLIDATED BALANCE SHEETS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETSParenthetical" roleURI="http://telos.com/role/CONSOLIDATEDBALANCESHEETSParenthetical">
        <link:definition>0000005 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCASHFLOWS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS">
        <link:definition>0000006 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY">
        <link:definition>0000007 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ORGANIZATION" roleURI="http://telos.com/role/ORGANIZATION">
        <link:definition>0000008 - Disclosure - ORGANIZATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIES" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIES">
        <link:definition>0000009 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITION" roleURI="http://telos.com/role/REVENUERECOGNITION">
        <link:definition>0000010 - Disclosure - REVENUE RECOGNITION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENET" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENET">
        <link:definition>0000011 - Disclosure - ACCOUNTS RECEIVABLE, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNET" roleURI="http://telos.com/role/INVENTORIESNET">
        <link:definition>0000012 - Disclosure - INVENTORIES, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNET" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNET">
        <link:definition>0000013 - Disclosure - PROPERTY AND EQUIPMENT, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GOODWILL" roleURI="http://telos.com/role/GOODWILL">
        <link:definition>0000014 - Disclosure - GOODWILL</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNET" roleURI="http://telos.com/role/INTANGIBLEASSETSNET">
        <link:definition>0000015 - Disclosure - INTANGIBLE ASSETS, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTS" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTS">
        <link:definition>0000016 - Disclosure - OTHER BALANCE SHEET COMPONENTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONS" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONS">
        <link:definition>0000017 - Disclosure - DEBT AND OTHER OBLIGATIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACQUISITION" roleURI="http://telos.com/role/ACQUISITION">
        <link:definition>0000018 - Disclosure - ACQUISITION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATION" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATION">
        <link:definition>0000019 - Disclosure - STOCK-BASED COMPENSATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SHAREREPURCHASES" roleURI="http://telos.com/role/SHAREREPURCHASES">
        <link:definition>0000020 - Disclosure - SHARE REPURCHASES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSS" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSS">
        <link:definition>0000021 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHARE" roleURI="http://telos.com/role/LOSSPERSHARE">
        <link:definition>0000022 - Disclosure - LOSS PER SHARE</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RELATEDPARTYTRANSACTIONS" roleURI="http://telos.com/role/RELATEDPARTYTRANSACTIONS">
        <link:definition>0000023 - Disclosure - RELATED PARTY TRANSACTIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATION" roleURI="http://telos.com/role/SEGMENTINFORMATION">
        <link:definition>0000024 - Disclosure - SEGMENT INFORMATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="COMMITMENTSANDCONTINGENCIES" roleURI="http://telos.com/role/COMMITMENTSANDCONTINGENCIES">
        <link:definition>0000025 - Disclosure - COMMITMENTS AND CONTINGENCIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATION" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATION">
        <link:definition>0000026 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTS" roleURI="http://telos.com/role/REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTS">
        <link:definition>0000027 - Disclosure - REVISION OF PRIOR YEAR INTERIM FINANCIAL STATEMENTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESPolicies" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESPolicies">
        <link:definition>0000028 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESTables" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESTables">
        <link:definition>0000029 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONTables" roleURI="http://telos.com/role/REVENUERECOGNITIONTables">
        <link:definition>0000030 - Disclosure - REVENUE RECOGNITION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETTables" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETTables">
        <link:definition>0000031 - Disclosure - ACCOUNTS RECEIVABLE, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNETTables" roleURI="http://telos.com/role/INVENTORIESNETTables">
        <link:definition>0000032 - Disclosure - INVENTORIES, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNETTables" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNETTables">
        <link:definition>0000033 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETTables" roleURI="http://telos.com/role/INTANGIBLEASSETSNETTables">
        <link:definition>0000034 - Disclosure - INTANGIBLE ASSETS, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSTables" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSTables">
        <link:definition>0000035 - Disclosure - OTHER BALANCE SHEET COMPONENTS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONTables" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONTables">
        <link:definition>0000036 - Disclosure - STOCK-BASED COMPENSATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSSTables" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSSTables">
        <link:definition>0000037 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHARETables" roleURI="http://telos.com/role/LOSSPERSHARETables">
        <link:definition>0000038 - Disclosure - LOSS PER SHARE (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONTables" roleURI="http://telos.com/role/SEGMENTINFORMATIONTables">
        <link:definition>0000039 - Disclosure - SEGMENT INFORMATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONTables" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONTables">
        <link:definition>0000040 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTSTables" roleURI="http://telos.com/role/REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTSTables">
        <link:definition>0000041 - Disclosure - REVISION OF PRIOR YEAR INTERIM FINANCIAL STATEMENTS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ORGANIZATIONNarrativeDetails" roleURI="http://telos.com/role/ORGANIZATIONNarrativeDetails">
        <link:definition>0000042 - Disclosure - ORGANIZATION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails">
        <link:definition>0000043 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESChangesinRestructuringExpensesAccrualDetails" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESChangesinRestructuringExpensesAccrualDetails">
        <link:definition>0000044 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Changes in Restructuring Expenses Accrual (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONNarrativeDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONNarrativeDetails">
        <link:definition>0000045 - Disclosure - REVENUE RECOGNITION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONNarrativeDetails_1" roleURI="http://telos.com/role/REVENUERECOGNITIONNarrativeDetails_1">
        <link:definition>0000045 - Disclosure - REVENUE RECOGNITION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONRevenuebyCustomerTypeDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONRevenuebyCustomerTypeDetails">
        <link:definition>0000046 - Disclosure - REVENUE RECOGNITION - Revenue by Customer Type (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONScheduleofContractBalancesDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONScheduleofContractBalancesDetails">
        <link:definition>0000047 - Disclosure - REVENUE RECOGNITION - Schedule of Contract Balances (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETDetails" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETDetails">
        <link:definition>0000048 - Disclosure - ACCOUNTS RECEIVABLE, NET (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETNarrativeDetails" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETNarrativeDetails">
        <link:definition>0000049 - Disclosure - ACCOUNTS RECEIVABLE, NET - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNETDetails" roleURI="http://telos.com/role/INVENTORIESNETDetails">
        <link:definition>0000050 - Disclosure - INVENTORIES, NET (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNETPropertyPlantandEquipmentDetails" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNETPropertyPlantandEquipmentDetails">
        <link:definition>0000051 - Disclosure - PROPERTY AND EQUIPMENT, NET - Property, Plant and Equipment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNETNarrativeDetails" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNETNarrativeDetails">
        <link:definition>0000052 - Disclosure - PROPERTY AND EQUIPMENT, NET - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GOODWILLDetails" roleURI="http://telos.com/role/GOODWILLDetails">
        <link:definition>0000053 - Disclosure - GOODWILL (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETScheduleofIntangibleAssetsNetDetails" roleURI="http://telos.com/role/INTANGIBLEASSETSNETScheduleofIntangibleAssetsNetDetails">
        <link:definition>0000054 - Disclosure - INTANGIBLE ASSETS, NET - Schedule of Intangible Assets, Net (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETNarrativeDetails" roleURI="http://telos.com/role/INTANGIBLEASSETSNETNarrativeDetails">
        <link:definition>0000055 - Disclosure - INTANGIBLE ASSETS, NET - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSAccountsPayableandOtherAccruedLiabilitiesDetails" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSAccountsPayableandOtherAccruedLiabilitiesDetails">
        <link:definition>0000056 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Accounts Payable and Other Accrued Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSOtherCurrentLiabilitiesDetails" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSOtherCurrentLiabilitiesDetails">
        <link:definition>0000057 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Other Current Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONSRevolvingCreditFacilityDetails" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONSRevolvingCreditFacilityDetails">
        <link:definition>0000058 - Disclosure - DEBT AND OTHER OBLIGATIONS - Revolving Credit Facility (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONSOtherFinancingObligationsDetails" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONSOtherFinancingObligationsDetails">
        <link:definition>0000059 - Disclosure - DEBT AND OTHER OBLIGATIONS - Other Financing Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACQUISITIONNarrativeDetails" roleURI="http://telos.com/role/ACQUISITIONNarrativeDetails">
        <link:definition>0000060 - Disclosure - ACQUISITION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONNarrativeDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONNarrativeDetails">
        <link:definition>0000061 - Disclosure - STOCK-BASED COMPENSATION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONStockBasedCompensationExpenseIncurredDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONStockBasedCompensationExpenseIncurredDetails">
        <link:definition>0000062 - Disclosure - STOCK-BASED COMPENSATION - Stock-Based Compensation Expense Incurred (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONNonvestedRestrictedStockUnitsActivityDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONNonvestedRestrictedStockUnitsActivityDetails">
        <link:definition>0000063 - Disclosure - STOCK-BASED COMPENSATION - Nonvested Restricted Stock Units Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SHAREREPURCHASESNarrativeDetails" roleURI="http://telos.com/role/SHAREREPURCHASESNarrativeDetails">
        <link:definition>0000064 - Disclosure - SHARE REPURCHASES - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSSDetails" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSSDetails">
        <link:definition>0000065 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHAREDetails" roleURI="http://telos.com/role/LOSSPERSHAREDetails">
        <link:definition>0000066 - Disclosure - LOSS PER SHARE (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RELATEDPARTYTRANSACTIONSDetails" roleURI="http://telos.com/role/RELATEDPARTYTRANSACTIONSDetails">
        <link:definition>0000067 - Disclosure - RELATED PARTY TRANSACTIONS (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONNarrativeDetails" roleURI="http://telos.com/role/SEGMENTINFORMATIONNarrativeDetails">
        <link:definition>0000068 - Disclosure - SEGMENT INFORMATION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONOperationsbyBusinessSegmentDetails" roleURI="http://telos.com/role/SEGMENTINFORMATIONOperationsbyBusinessSegmentDetails">
        <link:definition>0000069 - Disclosure - SEGMENT INFORMATION - Operations by Business Segment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONCashCashEquivalentsandRestrictedCashDetails" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONCashCashEquivalentsandRestrictedCashDetails">
        <link:definition>0000070 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION - Cash, Cash Equivalents, and Restricted Cash (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONSupplementalCashFlowInformationDetails" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONSupplementalCashFlowInformationDetails">
        <link:definition>0000071 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION - Supplemental Cash Flow Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTSNarrativeDetails" roleURI="http://telos.com/role/REVISIONOFPRIORYEARINTERIMFINANCIALSTATEMENTSNarrativeDetails">
        <link:definition>0000072 - Disclosure - REVISION OF PRIOR YEAR INTERIM FINANCIAL STATEMENTS - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAStatementofOperationsDetails" roleURI="http://telos.com/role/REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAStatementofOperationsDetails">
        <link:definition>0000073 - Disclosure - REVISION OF UNAUDITED QUARTERLY FINANCIAL DATA - Statement of Operations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAComprehensiveLossDetails" roleURI="http://telos.com/role/REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAComprehensiveLossDetails">
        <link:definition>0000074 - Disclosure - REVISION OF UNAUDITED QUARTERLY FINANCIAL DATA - Comprehensive Loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAStatementofStockholdersEquityDetails" roleURI="http://telos.com/role/REVISIONOFUNAUDITEDQUARTERLYFINANCIALDATAStatementofStockholdersEquityDetails">
        <link:definition>0000075 - Disclosure - REVISION OF UNAUDITED QUARTERLY FINANCIAL DATA - Statement of Stockholders' Equity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="tls_AlternativeBaseRateMember" abstract="true" name="AlternativeBaseRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_BusinessCombinationConsiderationTransferredLiabilitiesIncurredCashHoldbackPeriod" abstract="false" name="BusinessCombinationConsiderationTransferredLiabilitiesIncurredCashHoldbackPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="tls_CostPlusFixedFeeMember" abstract="true" name="CostPlusFixedFeeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_OtherFinancingObligationsCurrent" abstract="false" name="OtherFinancingObligationsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_DebtInstrumentIncrementalIncreaseInInterestRateDueToDefault" abstract="false" name="DebtInstrumentIncrementalIncreaseInInterestRateDueToDefault" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="tls_OtherAccruedExpensesCurrent" abstract="false" name="OtherAccruedExpensesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_StateLocalAndCommercialMember" abstract="true" name="StateLocalAndCommercialMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_OtherCurrentLiabilitiesOther" abstract="false" name="OtherCurrentLiabilitiesOther" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_SoftwareLicenseDeliveryOrderNumberOfExercisableExtensionOptions" abstract="false" name="SoftwareLicenseDeliveryOrderNumberOfExercisableExtensionOptions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="tls_RevenueTimingOfTransferOfGoodsOrServiceMember" abstract="true" name="RevenueTimingOfTransferOfGoodsOrServiceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_WithholdingTaxOnNetShareSettlementUnderOtherCurrentLiabilities" abstract="false" name="WithholdingTaxOnNetShareSettlementUnderOtherCurrentLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_AcquiredTechnologyAndCustomerRelationshipsMember" abstract="true" name="AcquiredTechnologyAndCustomerRelationshipsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_Two016OmnibusLongTermIncentivePlanMember" abstract="true" name="Two016OmnibusLongTermIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_IntangibleAssetsTransferredToExtinguishOtherFinancingObligations" abstract="false" name="IntangibleAssetsTransferredToExtinguishOtherFinancingObligations" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_SecureNetworksSegmentMember" abstract="true" name="SecureNetworksSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_DiamondFortressTechnologiesMember" abstract="true" name="DiamondFortressTechnologiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_AdjustedDailySimpleSecuredOvernightFinancingRateSOFRMember" abstract="true" name="AdjustedDailySimpleSecuredOvernightFinancingRateSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_BillContractsReceivableNetOfAllowance" abstract="false" name="BillContractsReceivableNetOfAllowance" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_USDepartmentOfDefenseMember" abstract="true" name="USDepartmentOfDefenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_AssetPurchaseAgreementMember" abstract="true" name="AssetPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ShareBasedPaymentArrangementTrancheFourMember" abstract="true" name="ShareBasedPaymentArrangementTrancheFourMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_CivilianMember" abstract="true" name="CivilianMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_SoftwareLicensesUnderDeliveryOrderMember" abstract="true" name="SoftwareLicensesUnderDeliveryOrderMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_NumberOfSharesHeldByRelatedParty" abstract="false" name="NumberOfSharesHeldByRelatedParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="tls_EmmettWoodMember" abstract="true" name="EmmettWoodMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_OtherFinancingObligationsNoncurrent" abstract="false" name="OtherFinancingObligationsNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_FurnitureAndEquipmentMember" abstract="true" name="FurnitureAndEquipmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_SecuritySolutionsSegmentMember" abstract="true" name="SecuritySolutionsSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_AdjustedTermSecuredOvernightFinancingRateSOFRMember" abstract="true" name="AdjustedTermSecuredOvernightFinancingRateSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_PaymentOfDFTHoldbackAmount" abstract="false" name="PaymentOfDFTHoldbackAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_SoftwareLicenseDeliveryOrderPeriodOfExercisableExtensionOptions" abstract="false" name="SoftwareLicenseDeliveryOrderPeriodOfExercisableExtensionOptions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="tls_CreditAgreementMember" abstract="true" name="CreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ConsultingServicesContractOptionToExtendPeriod" abstract="false" name="ConsultingServicesContractOptionToExtendPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="tls_IncrementalCommonSharesExcludedFromTheDilutiveEffect" abstract="false" name="IncrementalCommonSharesExcludedFromTheDilutiveEffect" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="tls_TelosIdMember" abstract="true" name="TelosIdMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ServiceBasedRSUAwardsMember" abstract="true" name="ServiceBasedRSUAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" abstract="false" name="LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_DebtInstrumentCovenantSeniorLeverageRatioMaximum" abstract="false" name="DebtInstrumentCovenantSeniorLeverageRatioMaximum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="tls_FederalGovernmentMember" abstract="true" name="FederalGovernmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
