UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE

SECURITIES EXCHANGE ACT OF 1934

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Filed by a Party other than the Registrant ☐
Check the appropriate box:
☐	Preliminary Proxy Statement
☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting Material Under §240.14a-12

BLACKLINE, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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☒	No fee required
☐	Fee paid previously with preliminary materials
☐	Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

Your Vote Counts! *Please check the meeting materials for any special requirements for meeting attendance. Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # V66469-P26887 BLACKLINE, INC. 21300 VICTORY BLVD, 12TH FLOOR WOODLAND HILLS, CA 91367 BLACKLINE, INC. 2025 Annual Meeting Vote by May 7, 2025 11:59 p.m. ET You invested in BLACKLINE, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the shareholder meeting to be held on May 8, 2025. Vote Virtually at the Meeting* May 8, 2025 9:00 a.m. PT Virtually at: www.virtualshareholdermeeting.com/BL2025 Get informed before you vote View the Notice and Proxy Statement and Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to April 24, 2025. If you would like to request a copy of the material(s) for this and/or future shareholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy.

Vote at www.ProxyVote.com Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Delivery Settings”. Voting Items Board Recommends V66470-P26887 THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming shareholder meeting. Please follow the instructions on the reverse side to vote these important matters. 1. Election of Directors For Nominees: 01) Camille Drummond 02) Brunilda Rios 03) Barbara Whye 04) Mika Yamamoto 2. To ratify the appointment of PricewaterhouseCoopers LLP (“PwC”) as the Company’s independent registered public accounting firm for its fiscal year ending December 31, 2025. For 3. Approval, on a non-binding, advisory basis, of the 2024 compensation of the Company’s named executive officers. For 4. Approval, on a non-binding, advisory basis, on the frequency of future advisory votes on the compensation of the Company’s named executive officers. 1 Year NOTE: In their discretion, the proxies are authorized to vote upon such other business as may properly come before the Annual Meeting of Shareholders or any adjournments or postponements thereof.