FORM 11-K (Mark One) ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIESEXCHANGE ACT OF 1934 For the fiscal year ended December31, 2025 OR TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIESEXCHANGE ACT OF 1934 For the transition period fromto. Commission file number 0-16772 A. Full title of the plan and the address of the plan, if different from that of the issuer named below: Peoples Bancorp Inc. Retirement Savings Plan138 Putnam Street, P.O. Box 738Marietta, Ohio 45750Attn: Peoples Bancorp Inc. Retirement Plan Committee B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office: Peoples Bancorp Inc.138 Putnam Street, P.O. Box 738Marietta, Ohio 45750 Peoples Bancorp Inc. Retirement Savings Plan December 31, 2025 and 2024Table of Contents Report of Independent Registered Public Accounting Firm Financial StatementsStatements of Net Assets Available for BenefitsStatements of Changes in Net Assets Available for BenefitsNotes to Financial Statements Supplemental ScheduleSchedule H, Line 4i - Schedule of Assets (Held at End of Year) Exhibit Index Signatures13 Report of Independent Registered Public Accounting Firm To the Plan AdministratorPeoples Bancorp Inc. Retirement Savings PlanMarietta, Ohio Opinion on the Financial StatementsWe have audited the accompanying statements of net assets available for benefits of the Peoples Bancorp Inc. Retirement Savings Plan (the “Plan”) as of December 31, 2025 and 2024; the related statement of changes in net assets available for benefits for the year ended December31, 2025;and the related notes to the financial statements (collectively, the financial statements). In our opinion, the financial statementspresent fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, 2025 and 2024, and the changes in netassets available for benefits for the year ended December 31, 2025, in conformity with accounting principles generally accepted in the UnitedStates of America.Basis for Opinion These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on the Plan’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (UnitedStates) (PCAOB) and are required to be independent with respect to the Plan, in accordance with U.S. federal securities laws and the applicablerules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtainreasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Plan is notrequired to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are requiredto obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness ofthe Plan’s internal control over financial reporting. Accordingly, we express no such opinion. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error orfraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding theamounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significantestimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide areasonable basis for our opinion. Supplemental Information The supplemental information in the accompanying schedule, Schedule H, Line 4i – Schedule of Assets (Held at End of Year) as of December31, 2025, has been subjected to audit procedures performed in conjunction with the audit of the Plan’s financial statements. The supplementalinformation is presented for the purpose of additional analysis and is not a required part of the financial statements but includes supplementalinformation required by the Department of Labor (DOL)’s Rules and Regulations for Reporting and Disclosure under the Employee RetirementIncome Security Act of 1974. The supplemental information is the responsibility of the Plan’s management. Our audit procedures includeddetermining whether the supplemental information reconciles to the financial statements or the underlying accounting and other records, asapplicable, and performing procedures to test the completeness and accuracy of the information presented in the supplemental information. Informing our opinion on the supplemental information in the accompanying schedule, we evaluated whether the supplemental information,including its form and content, i