Exhibit 23.1
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We consent to the incorporation by reference in Registration Statement No. 333-144403 of Huntington
Bancshares Incorporated on Form S-8 of our report dated June 29, 2009 (which report expresses an
unqualified opinion and includes an explanatory paragraph relating to the plan termination and the
liquidation basis of accounting), appearing in this Annual Report on
Form 11-K of the Sky Financial
Group, Inc. Profit Sharing, 401(k) and ESOP Plan for the year ended December 31, 2008.
/s/ Deloitte & Touche LLP
Columbus, Ohio
June 29, 2009