EXHIBIT 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-3 (Registration Nos. 333-59154, 333-103376, 333-0108929, and 333-107814) and Form S-8 (Registration Nos. 333-52620, 333-91434, 333-99853, 333-103242, 333-117763, 333-119767, 333-138328, 333-152254, and 333-158280) of Mercantile Bank Corporation of our reports dated March 15, 2010 relating to the consolidated financial statements and the effectiveness of Mercantile Bank Corporation’s internal control over financial reporting, which appear in this Annual Report on Form 10-K.

/s/ BDO Seidman, LLP  

BDO Seidman, LLP 

Grand Rapids, Michigan  

March 15, 2010