<SEC-DOCUMENT>0001841654-25-000005.txt : 20251002
<SEC-HEADER>0001841654-25-000005.hdr.sgml : 20251002
<ACCEPTANCE-DATETIME>20251002160224
ACCESSION NUMBER:		0001841654-25-000005
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250930
FILED AS OF DATE:		20251002
DATE AS OF CHANGE:		20251002

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Sharan Sharat
		CENTRAL INDEX KEY:			0001841654
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39965
		FILM NUMBER:		251368834

	MAIL ADDRESS:	
		STREET 1:		50 BEALE STREET, 8TH FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ON24 INC.
		CENTRAL INDEX KEY:			0001110611
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		ORGANIZATION NAME:           	06 Technology
		EIN:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		50 BEALE STREET, 8TH FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105
		BUSINESS PHONE:		(415) 369-8000

	MAIL ADDRESS:	
		STREET 1:		50 BEALE STREET, 8TH FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ON24 INC
		DATE OF NAME CHANGE:	20000329
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-09-30</periodOfReport>

    <notSubjectToSection16>false</notSubjectToSection16>

    <issuer>
        <issuerCik>0001110611</issuerCik>
        <issuerName>ON24 INC.</issuerName>
        <issuerTradingSymbol>ONTF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001841654</rptOwnerCik>
            <rptOwnerName>Sharan Sharat</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ON24, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>50 BEALE STREET, 8TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94015</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>President and Chief Executive</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>true</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2025-09-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>29457.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.7376</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3591406.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2025-10-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20873.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.6047</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3570533.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the number of shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units.</footnote>
        <footnote id="F2">The transaction reported in this Form 4 was effected pursuant to a Rule 10B5-1 trading plan adopted by the reporting person on December 12, 2024.</footnote>
        <footnote id="F3">The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $5.69 to $5.825 inclusive. The reporting person undertakes to provide to Issuer, any security holder of Issuer, or the staff of the Security and Exchange Commission, upon request, full information regarding the number of shares sold in each separate price within the ranges set forth in footnote (3) to this Form 4.</footnote>
        <footnote id="F4">The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $5.51 to $5.68 inclusive. The reporting person undertakes to provide to Issuer, any security holder of Issuer, or the staff of the Security and Exchange Commission, upon request, full information regarding the number of shares sold in each separate price within the ranges set forth in footnote (4) to this Form 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Sharan Sharat by Charles Rogerson, as Attorney-in-Fact</signatureName>
        <signatureDate>2025-10-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
