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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2017-01-10</periodOfReport>

    <dateOfOriginalSubmission>2017-01-13</dateOfOriginalSubmission>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001679688</issuerCik>
        <issuerName>Colony NorthStar, Inc.</issuerName>
        <issuerTradingSymbol>CLNS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001497786</rptOwnerCik>
            <rptOwnerName>Schoenherr Charles W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COLONY NORTHSTAR, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>515 S. FLOWER ST., 44TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <remarks>This amendment to the Initial Statement of Beneficial Ownership of Securities on Form 3, filed with the Securities and Exchange Commission on January 13, 2017, is being filed solely to amend the Power of Attorney filed as Exhibit 24.</remarks>

    <ownerSignature>
        <signatureName>/s/ David A. Palame, Attorney-in-Fact</signatureName>
        <signatureDate>2017-01-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
