CIVISTA BANCSHARES, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

Check the appropriate box:

(Name of registrant as specified in its charter)

(Name of person(s) filing proxy statement, if other than the registrant)

Payment of Filing Fee (Check all boxes that apply):

NOTICE OF 2026 ANNUAL MEETING OF SHAREHOLDERS & PROXY STATEMENT CIVISTA BANCSHARES, INC. Rooted in Community, Focused on the Future. NASDAQ: CIVB | civb.com | civista.bank

P.O. Box 5016½ Sandusky, Ohio 44870

NOTICE OF ANNUAL MEETING OF SHAREHOLDERS

TO BE HELD ON MAY 19, 2026

TO ALL SHAREHOLDERS:

Notice is hereby given that the Annual Meeting of Shareholders (the “Annual Meeting”) of Civista Bancshares, Inc. (the “Corporation”) will be held at Sawmill Creek Resort, 400 Sawmill Creek Drive, Huron, Ohio 44839, at 10:00 AM Eastern Time on Tuesday, May 19, 2026, for the following purposes:

Only those holders of record of common shares of the Corporation at the close of business on March 24, 2026, will be entitled to notice of and to vote at the Annual Meeting.

A Notice of Internet Availability of Proxy Materials is being sent to shareholders on or about April 7, 2026. The Notice of Internet Availability of Proxy Materials contains instructions on how to access the Corporation’s Proxy Statement for the 2026 Annual Meeting and the Corporation’s 2025 Annual Report to Shareholders. Copies of the Corporation’s Proxy Statement, a form of proxy card and the 2025 Annual Report to Shareholders can be requested free of charge at the following Internet address: www.proxydocs.com/CIVB.

HOW TO VOTE

We encourage our shareholders to enroll in e-delivery for future proxy materials. Electronic delivery is convenient and provides immediate access to these materials. This will help us saving printing and mailing expenses, and will reduce our impact on the environment. Follow the simple instructions at www.proxydocs.com/CIVB.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF SHAREHOLDERS TO BE HELD ON MAY 19, 2026: The

Corporation’s Proxy Statement for the Annual Meeting, a sample of the form of proxy card and the Corporation’s 2025 Annual Report to Shareholders are available at www.proxydocs.com/CIVB.

Before making any voting decisions, you are urged to read the Corporation’s Proxy Statement for the Annual Meeting (including any amendments or supplements thereto) and any other relevant documents that the Corporation may file with or furnish to the SEC.

You are cordially invited to attend the Annual Meeting. Your vote is very important, regardless of the number of common shares you own. Whether or not you plan to attend the Annual Meeting in person, it is important that your common shares be represented. Please vote as soon as possible by following the instructions in your Notice of Internet Availability of Proxy Materials. You may vote electronically via the Internet or by using the toll-free telephone number provided, or by completing and returning a proxy card by mail if you requested or received paper materials. A return envelope, which requires no postage if mailed in the United States, will be provided with mailed proxy materials. You may also cast your vote in person at the Annual Meeting; however, if you are not the record holder of your common shares, you must bring documentation from your broker, financial institution, or other nominee authorizing you to vote on behalf of the record holder of your shares.

To obtain driving directions to attend the Annual Meeting, please contact Karen Terenzi(419-609-1347; kmterenzi@civista.bank) or Lori Castillo(419-627-4554; lacastillo@civista.bank).

By Order of the Board of Directors

Lance A. Morrison, Corporate Secretary

Civista Bancshares, Inc.

April 7, 2026