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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-06-05</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001770141</issuerCik>
        <issuerName>GigCapital2, Inc.</issuerName>
        <issuerTradingSymbol>GIX.U</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001451693</rptOwnerCik>
            <rptOwnerName>Katz Avi S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GIGCAPITAL2, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2479 E. BAYSHORE RD., SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94303</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO, Pres, Exec Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001778960</rptOwnerCik>
            <rptOwnerName>GigAcquisitions2, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GIGCAPITAL2, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>32479 E. BAYSHORE RD., SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94303</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3482500</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By GigAcquisitions2, LLC (see note below)</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes up to 454,891 shares of Common Stock that are subject to forfeiture depending on the extent to which the underwriters' over-allotment is exercised, if at all.</footnote>
        <footnote id="F2">The Common Stock is held directly by GigAcquisitions2, LLC (the &quot;Sponsor&quot;). The shares held by the Sponsor are beneficially owned by Dr. Avi S. Katz, GigCapital2, Inc.'s Chief Executive Officer, President, Executive Chairman of the Board of Directors, and Secretary. Dr. Katz is also the Manager of the Sponsor, who has sole voting and dispositive power over the shares held by the Sponsor.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Dr. Avi S. Katz, individually</signatureName>
        <signatureDate>2019-06-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Dr. Avi S. Katz, as Manager of GigAcquisitions2, LLC</signatureName>
        <signatureDate>2019-06-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
