<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2021-09-30</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001735707</issuerCik>
        <issuerName>Garrett Motion Inc.</issuerName>
        <issuerTradingSymbol>GTX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001887446</rptOwnerCik>
            <rptOwnerName>Pierce Tina</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>300 SOUTH TRYON STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <remarks>On September 30, 2021, Tina Pierce was appointed to the board of directors of Garrett Motion Inc. (the &quot;Company&quot;) as an appointee of Honeywell International Inc. (&quot;Honeywell&quot;) in replacement of Darius Adamczyk. As a result, Honeywell may be deemed to be a &quot;director by deputization&quot; of the Company for purposes of Section 16 of the Exchange Act. For further information, see Honeywell's initial statement of beneficial ownership on Form 3 filed on May 10, 2021 with respect to the Company.</remarks>

    <ownerSignature>
        <signatureName>/s/ Tina Pierce</signatureName>
        <signatureDate>2021-10-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
