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): September 6, 2012

ENBRIDGE ENERGY PARTNERS, L.P.

(Exact Name of Registrant as Specified in Charter)

1100 LOUISIANA, SUITE 3300, HOUSTON, TEXAS 77002

(Address of Principal Executive Offices) (Zip Code)

(713) 821-2000

(Registrant’s telephone number, including area code)

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

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 1.01. Entry into a Material Definitive Agreement.

On September 6, 2012, Enbridge Energy Partners, L.P., a Delaware limited partnership (the “Partnership”), entered into an underwriting agreement, filed as Exhibit 1.1 hereto, with the underwriters named therein with respect to the issue and sale by the Partnership of up to 16,100,000 Class A Common Units representing limited partner interests in the Partnership (including the underwriters’ over-allotment option to purchase up to 2,100,000 Class A Common Units) (the “Units”).

On September 6, 2012, pursuant to Rule 424(b)(5) under the Securities Act of 1933, as amended (the “Securities Act”), the Partnership filed with the U.S. Securities and Exchange Commission a Prospectus Supplement to its shelf registration statement on Form S-3 dated December 16, 2011 (Registration No. 333-178536) relating to the offering of the Units. Exhibits 1.1, 5.1, 8.1, 23.1 and 23.2 to this Current Report on Form 8-K relating to the offering of the Units are hereby incorporated by reference into such Registration Statement.

Item 7.01. Regulation FD Disclosure.

The Partnership issued a press release on September 6, 2012, attached hereto as Exhibit 99.1, announcing that it has priced the offering described in Item 1.01 of this Current Report on Form 8-K at an offering price to the public of $28.64 per Unit, before underwriters’ discounts and commissions and offering expenses. This information is not deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and is not incorporated by reference into any Securities Act registration statements.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Reference is made to the “Index of Exhibits” following the signature page, which is hereby incorporated into this Item.

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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 thereunto duly authorized.

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Index of Exhibits

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