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 27, 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):

Indenture and Supplemental Indenture

On May 12, 2014, Suburban Propane Partners, L.P. (“Suburban Propane”), entered into a previously announced underwriting agreement with Suburban Propane, L.P., Suburban Energy Finance Corp. and Wells Fargo Securities, LLC, as representative of the several underwriters named therein (the “Underwriters”), pursuant to which Suburban Propane and Suburban Energy Finance Corp., a wholly-owned direct subsidiary (the “Corporation,” together with Suburban Propane, “Suburban”), sold $525,000,000 aggregate principal amount of 5.50% senior notes due June 1, 2024 (the “2024 Notes”).

On May 27, 2014, the 2024 Notes were issued under, and Suburban entered into, (1) an indenture for senior debt securities (the “2024 Notes Base Indenture”) with The Bank of New York Mellon, as trustee (the “Trustee”), and (2) a first supplemental indenture with the Trustee (the “2024 Notes Supplemental Indenture” and, together with the 2024 Notes Base Indenture, the “2024 Notes Indenture”).

The 2024 Notes will bear interest at a rate of 5.50% per year, payable semiannually in arrears on June 1 and December 1 of each year, beginning on December 1, 2014.

The 2024 Notes will be unsecured, senior obligations and rank senior in right of payment to any future subordinated indebtedness and pari passu in right of payment to all of Suburban’s existing and future unsecured senior indebtedness. The 2024 Notes will be structurally subordinated to the indebtedness and other liabilities of all of Suburban’s subsidiaries, including the indebtedness and other liabilities of its operating partnership, Suburban Propane L.P., and its subsidiaries.

The 2024 Notes Indenture contains covenants that, among other things, limit Suburban’s ability and the ability of Suburban’s restricted subsidiaries (as defined in the 2024 Notes Indenture) to:

These covenants are subject to important limitations and exceptions that are described in the 2024 Notes Indenture.

The 2024 Notes were offered pursuant to a shelf registration statement on Form S-3 (File No. 333-195864), which became effective upon its filing with the Securities and Exchange Commission on May 12, 2014. A Preliminary Prospectus Supplement dated May 12, 2014 relating to the 2024 Notes and supplementing the Prospectus was filed with the SEC on May 12, 2014, and a final Prospectus Supplement dated May 12, 2014 was filed with the SEC on May 13, 2014.

The net proceeds from the sale of the 2024 Notes were estimated to be approximately $517,125,000 (after deducting underwriting discounts and commissions but before deducting estimated expenses). 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.

The description of the 2024 Notes Base Indenture and the 2024 Notes Supplemental Indenture, each as a part of the 2024 Notes Indenture, in this Form 8-K is a summary and is qualified in its entirety by the terms of the 2024 Notes Indenture. Copies of the 2024 Notes Base Indenture and the 2024 Notes Supplemental Indenture are attached hereto as Exhibit 4.1 and Exhibit 4.2 and incorporated herein by reference. The form of 2024 Notes issued pursuant to the 2024 Notes Supplemental Indenture is included as Annex A to the 2024 Notes Supplemental Indenture and incorporated herein by reference.

Effective as of May 27, 2014, the indenture dated as of August 1, 2012, as amended by the first supplemental indenture dated as of May 23, 2014 (the “2018 Notes Indenture”), among Suburban and the Trustee governing Suburban’s 7-1/2 % senior notes due 2018 (the “2018 Notes”) has been satisfied and discharged by Suburban in respect of the 2018 Notes (but not in respect of the 7 3/8 % Notes due 2021) in accordance with the terms of the 2018 Notes Indenture. Using the net proceeds from the sale of the 2024 Notes and additional cash on hand, Suburban caused to be paid: (i) approximately $413,979,487.29 to holders of the 2018 Notes that tendered their 2018 Notes pursuant to the previously announced cash tender offer as of the consent payment date, consisting of (1) $397,904,112.15 of base consideration for the aggregate principal amount of 2018 Notes tendered; (2) $4,501,105.14 of accrued and unpaid interest on such tendered 2018 Notes; and (3) $11,574,270 of consent payments to eliminate substantially all of the restrictive covenants and eliminate or modify certain events of default and related provisions, in each case in respect of the 2018 Notes; and (ii) approximately $119,054,100 to the Trustee of the 2018 Notes Indenture in connection with the satisfaction and discharge of the remaining 2018 Notes. In connection with such satisfaction and discharge, Suburban will redeem, on October 1, 2014, any and all of the 2018 Notes that were not tendered and validly accepted prior to the Expiration Date or that were tendered and validly withdrawn prior to the Expiration Date.

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

The 2024 Notes Indenture contains a covenant that, among other things, restricts Suburban’s ability to pay dividends or distributions or redeem or repurchase capital stock. Information concerning the 2024 Notes Indenture is set forth in Item 1.01, which information is incorporated herein by reference into this Item 3.03.

On May 28, 2014, Suburban issued a press release announcing the settlement of $525,000,000 in aggregate principal amount of Suburban’s 5.50% senior notes due 2024 and the application of proceeds therefrom, a copy of which is attached hereto as Exhibit 99.1 and hereby is incorporated 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