UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported) August 9, 2013

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 8.01. Other Events.

On August 9, 2013, Consumers Energy Company (“Consumers”) issued and sold $325,000,000 principal amount of its 3.375% First Mortgage Bonds due 2023 (the “Bonds”), pursuant to a registration statement on Form S-3 that Consumers filed with the Securities and Exchange Commission utilizing a “shelf” registration process (No. 333-174906-01) (the “Registration Statement”), a Preliminary Prospectus Supplement dated August 5, 2013 to Prospectus dated June 15, 2011, an Issuer Free Writing Prospectus that included the final terms of the transaction, a Final Prospectus Supplement dated August 5, 2013 to Prospectus dated June 15, 2011 and an underwriting agreement among Consumers and the underwriters named in that agreement with respect to the Bonds. Consumers intends to use the net proceeds from the offering for general corporate purposes.

This Current Report on Form 8-K is being filed to file certain documents in connection with the offering as exhibits to the Registration Statement.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

This Form 8-K contains “forward-looking statements” as defined in Rule 3b-6 of the Securities Exchange Act of 1934, Rule 175 of the Securities Act of 1933, and relevant legal decisions. The forward-looking statements are subject to risks and uncertainties. All forward-looking statements should be considered in the context of the risk and other factors detailed from time to time in Consumers’ Securities and Exchange Commission filings. Forward-looking statements should be read in conjunction with “FORWARD-LOOKING STATEMENTS AND INFORMATION” and “RISK FACTORS” sections of Consumers’ Form 10-K, for the year ended December 31, 2012,

and as updated in Consumers’ Forms 10-Q. Consumers’ “FORWARD-LOOKING STATEMENTS AND INFORMATION” and “RISK FACTORS” sections are incorporated herein by reference and discuss important factors that could cause Consumers’ results to differ materially from those anticipated in such statements.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit Index