<SEC-DOCUMENT>0001209191-21-052348.txt : 20210818
<SEC-HEADER>0001209191-21-052348.hdr.sgml : 20210818
<ACCEPTANCE-DATETIME>20210818183026
ACCESSION NUMBER:		0001209191-21-052348
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210816
FILED AS OF DATE:		20210818
DATE AS OF CHANGE:		20210818

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Soroca Adam Lee
		CENTRAL INDEX KEY:			0001725125

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36384
		FILM NUMBER:		211187774

	MAIL ADDRESS:	
		STREET 1:		C/O THE RUBICON PROJECT, INC.
		STREET 2:		12181 BLUFF CREEK DR., 4TH FLOOR
		CITY:			PLAYA VISTA
		STATE:			CA
		ZIP:			90094

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MAGNITE, INC.
		CENTRAL INDEX KEY:			0001595974
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
		IRS NUMBER:				208881738
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		12181 BLUFF CREEK DRIVE, 4TH FLOOR
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90094
		BUSINESS PHONE:		310-207-0272

	MAIL ADDRESS:	
		STREET 1:		12181 BLUFF CREEK DRIVE, 4TH FLOOR
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90094

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RUBICON PROJECT, INC.
		DATE OF NAME CHANGE:	20140106
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001595974</issuerCik>
        <issuerName>MAGNITE, INC.</issuerName>
        <issuerTradingSymbol>MGNI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001725125</rptOwnerCik>
            <rptOwnerName>Soroca Adam Lee</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MAGNITE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>6080 CENTER DRIVE, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90045</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Product Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3396</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.82</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>335300</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents the non-discretionary sale of shares on behalf of the Reporting Person pursuant to an arrangement mandated by the Issuer to cover the tax withholding obligations associated with the vesting of restricted stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Aaron Saltz, attorney-in-fact</signatureName>
        <signatureDate>2021-08-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
