Bank of Marin Bancorp

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 (Amendment No. )

Payment of Filing Fee (Check the appropriate box):

Proxy

Statement

Wednesday, May 27, 2026

Buck Institute for Research on Aging

8001 Redwood Boulevard

Novato, California

Dear Fellow Shareholders,

Thank you for your continued confidence and support. The past year brought its share of economic uncertainty, yet 2025 proved to be another strong year for our company. Improving loan growth, disciplined risk management, and thoughtful deposit pricing helped us remain on track. Growth in our deposit base came from delivering an exceptional banking experience—one built on trust, service, and relationships—not from competing on the highest rates. In addition, the strength of our balance sheet allowed us to take advantage of securities repositioning opportunities that improved our net interest margin and contributed meaningfully to core profitability. Asset quality improved throughout the year, and careful expense management allowed us to continue investing in the talent and technology that position us well for long-term success.

Looking ahead to 2026, the path forward appears promising. Economic conditions across our markets remain generally healthy, and the ongoing improvement in credit quality reinforces the strength of our lending practices. A strong loan pipeline, supported by healthy demand, gives us confidence in our ability to continue to improve loan growth in the coming year. We expect to build on our enviable deposit base as we deepen existing client relationships and cultivate new ones.

The momentum built in 2025 sets the stage for further progress in 2026. Continued net interest margin expansion, balance sheet growth, and increasing profitability enhance our capacity to invest strategically in both people and initiatives that drive the future of our franchise. These efforts aim to create lasting value for you—our shareholders—while ensuring we remain a trusted financial partner in our communities.

Thank you for your ongoing trust and support. We remain committed to prudent decision making, operational discipline, and creating sustainable value for all shareholders.

Sincerely,

Notice of Annual Meeting of Shareholders

To Our Shareholders:

Notice is hereby given of the Annual Meeting of Shareholders of Bank of Marin Bancorp. The meeting will be held at 4:00 p.m. Pacific Time on Wednesday, May 27, 2026 at the Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, California. A reception at the Buck Institute for Research on Aging will immediately follow the Annual Meeting.

You are urged to read the accompanying Proxy Statement carefully. It contains a detailed explanation of all matters on which you will be asked to vote.

Only shareholders of record as of the close of business on April 8, 2026 are entitled to receive notice of and to vote at this meeting.

Your vote is important to us. Whether or not you expect to attend the Annual Meeting, please submit a proxy as soon as possible to instruct how your shares are to be voted at the Annual Meeting. If you participate in and vote your shares at the Annual Meeting, your proxy will not be used.

If you would like to attend the Annual Meeting, you must pre-register atwww.bankofmarin.com/annual meeting by May 20, 2026**.** For questions, email events@bankofmarin.com.

Our bylaws provide that nominations for election to the board of directors of the Company may be made by the board of directors or by any shareholder of the Company’s stock entitled to vote for the election of directors. Nominations, other than those made by or on behalf of the existing management of the Company, must be made in writing and delivered or mailed to the Chairman of the Board or the Chief Executive Officer not less than 14 days nor more than 50 days prior to any meeting of shareholders called for the election of directors. The notification of nomination should contain the following information to the extent known by the notifying shareholder: (a) name and address of the proposed nominee(s); (b) principal occupation of the proposed nominee(s); (c) total number of shares that will be voted for the proposed nominee(s); (d) name and residence address of the notifying shareholder; and (e) number of shares owned by the notifying shareholder. Nominations not made in accordance with this section may be disregarded by the Chair of the meeting, and upon instruction, the Inspector of Election shall disregard all votes cast for each such nominee.

One copy of the Annual Report on Form 10-K and Proxy Statement is being delivered to multiple shareholders sharing an address unless the Company has received contrary instructions from one or more of the shareholders. The Company will deliver promptly upon written or oral request a separate copy of the Annual Report and Proxy Statement to a shareholder at a shared address to which a single copy of the document was delivered. If a shareholder wishes to receive a separate copy or has received multiple copies at one address and would like to receive a single copy in the future, please contact Computershare Investor Services by phone at (800) 368-5948 or by written request to Bank of Marin Bancorp c/o Computershare Investor Services, P.O. Box 43006, Providence, RI 02940-3006. Overnight correspondence should be mailed to Bank of Marin Bancorp c/o Computershare Investor Services, 150 Royall St., Suite 101, Canton MA 02021. The shareholder website iswww.computershare.com/investor.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE MEETING OF SHAREHOLDERS TO BE HELD ON MAY 27, 2026

Copies of the Annual Meeting Proxy Material, including the Proxy Statement and the Annual Report on Form 10- K, are also available at:www.edocumentview.com/BMRC**.**

By order of the Board of Directors,

Krissy Meyer

Corporate Secretary

April 22, 2026