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): May 12, 2014

SUBURBAN PROPANE PARTNERS, L.P.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code (973) 887-5300

(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 (see General Instruction A.2. below):

Underwriting Agreement

On May 12, 2014, Suburban Propane Partners, L.P. (“Suburban”) entered into an underwriting agreement (the “Underwriting Agreement”) with Suburban Energy Finance Corp. (the “Corporation,” together with Suburban, the “Issuers”), Suburban Propane, L.P. and Wells Fargo Securities, LLC, acting as representative of the several underwriters named therein (collectively, the “Underwriters”), providing for its underwritten public offering of $525 million aggregate principal amount of 5.50% senior notes due June 1, 2024. The Corporation, a wholly-owned direct subsidiary of Suburban, is the co-issuer of the notes. The offer and sale of the notes is registered under the Securities Act of 1933, as amended (the “Securities Act”), pursuant to an automatic shelf registration statement on Form S-3 (File No. 333-195864) filed with the SEC on May 12, 2014. Suburban expects the transaction to close on or about May 27, 2014.

In the Underwriting Agreement, the Issuers agreed to indemnify the Underwriters against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the Underwriters may be required to make because of any of those liabilities. The description of the Underwriting Agreement in this Form 8-K is a summary and is qualified in its entirety by the terms of the Underwriting Agreement. A copy of the Underwriting Agreement is filed as Exhibit 1.1 to this Form 8-K and is incorporated herein by reference.

Certain of the Underwriters and their related entities have engaged, and may in the future engage, in commercial and investment banking transactions with Suburban in the ordinary course of its business. Affiliates of certain Underwriters are lenders under Suburban’s credit facilities. These Underwriters and their related entities have received, and expect to receive, customary compensation and expense reimbursement for these commercial and investment banking transactions.

Dealer Manager Agreement

On May 12, 2014, the Issuers entered into a dealer manager agreement (the “Dealer Manager Agreement”) with Wells Fargo Securities, LLC (“WF” or the “Dealer Manager”), in connection with the Issuers’ tender offer for any and all of the $496.6 million of their outstanding 7.50 % senior notes due 2018 (CUSIP No. 864486AE5) (the “Tender Offer”) and a related solicitation of consents to certain proposed amendments to the indenture governing the senior notes due 2018. Suburban expects the Tender Offer to expire on June 9, 2014, unless extended by the Issuers.

In the Dealer Manager Agreement, the Issuers agreed to indemnify the Dealer Manager against certain liabilities. The description of the Dealer Manager Agreement in this Form 8-K is a summary and is qualified in its entirety by the terms of the Dealer Manager Agreement. A copy of the Dealer Manager Agreement is filed as Exhibit 10.1 to this Form 8-K and is incorporated herein by reference.

The Dealer Manager and its related entities have engaged, and may in the future engage, in commercial and investment banking transactions with Suburban in the ordinary course of its business. Affiliates of the Dealer Manager are lenders under Suburban’s credit facilities. The Dealer Manager and its related entities have received, and expect to receive, customary compensation and expense reimbursement for these commercial and investment banking transactions.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

The information contained in Item 1.01 of this Form 8-K is incorporated herein by reference.

On May 12, 2014, Suburban issued a press release announcing the pricing of its public offering of $525 million aggregate principal amount of 5.50% senior notes due 2024. A copy of the press release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference.

SIGNATURES

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