MERCANTILE BANK CORP

As of December 31, 2025, an evaluation was performed under the supervision of and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures. Based on that evaluation, our management, including our Chief Executive Officer and Chief Financial Officer, concluded that our disclosure controls and procedures were effective as of December 31, 2025.

There have been no significant changes in our internal control over financial reporting during the year ended December 31, 2025, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rules 13a-15(f). There are inherent limitations in the effectiveness of any system of internal control. Accordingly, even an effective system of internal control can provide only reasonable assurance with respect to financial statement preparation.

Under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, we conducted an evaluation of the effectiveness of our internal control over financial reporting as of December 31, 2025. This evaluation was based on criteria for effective internal control over financial reporting described inInternal Control–* Integrated Framework (2013)* issued by the Committee of Sponsoring Organizations of the Treadway Commission (“COSO”). Based on our evaluation under the COSO framework, our management concluded that our internal control over financial reporting was effective as of December 31, 2025. Refer to page F-26 for management’s report. The Report by Mercantile Bank Corporation’s Management on Internal Control Over Financial Reporting included in this Annual Report is incorporated here by reference.

Our independent registered public accounting firm has issued an audit report on our internal control over financial reporting which is included on page F-25 of this report. The Reports of the Independent Registered Public Accounting Firm included in this Annual Report are incorporated here by reference.