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 15, 2013

Plains All American Pipeline, L.P.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (713) 646-4100

(Former name or former address, if changed since last report): Not applicable

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):

On August 15, 2013 Plains All American Pipeline, L.P. (the “Partnership”) and PAA Finance Corp. (together with the Partnership, the “Issuers”) completed the public offering of $700 million aggregate principal amount of 3.850% Senior Notes due 2023 (the “Notes”).

The terms of the Notes are governed by the indenture (the “Base Indenture,” and as amended and supplemented by the Supplemental Indenture (defined below), the “Indenture”) dated as of September 25, 2002 by and among the Issuers and U.S. Bank National Association, as trustee (the “Trustee”), as supplemented by the Twenty-Fourth Supplemental Indenture between the Issuers and the Trustee (the “Supplemental Indenture”).

The Notes will mature on October 15, 2023. Interest is payable on the Notes on each April 15 and October 15, commencing on April 15, 2014. The Issuers may redeem some or all of the Notes at any time and from time to time prior to maturity at the redemption prices specified in the Indenture.

The Notes are the Partnership’s senior unsecured obligations, will rank equally in right of payment with all of the Partnership’s existing and future senior debt, and will rank senior in right of payment to all of the Partnership’s future subordinated debt. The Notes will be effectively subordinated to all of the Partnership’s existing and future secured debt to the extent of the value of the collateral securing such indebtedness.

In certain circumstances, the Indenture restricts the Partnership’s ability and the ability of certain of its subsidiaries to: (i) enter into sale and leaseback transactions; (ii) incur liens; (iii) merge or consolidate with another company; and (iv) transfer and sell assets. These covenants are subject to a number of important exceptions and qualifications.

The Indenture contains customary events of default with respect to the Notes of either series, including:

If an event of default under the Indenture occurs and is continuing, the Trustee or the holders of at least 25% in principal amount of the outstanding Notes may declare the principal of, premium, if any, and accrued and unpaid interest, if any, on the Notes to be due and payable, or, in the case of certain events of default relating to bankruptcy, insolvency or reorganization, those amounts will automatically become immediately due and payable.

Other material terms of the Notes, the Base Indenture and the Supplemental Indenture are described in the prospectus supplement, dated August 8, 2013, as filed by the Partnership with the Commission on August 9, 2013. The foregoing descriptions of the Indenture and the Notes are qualified in their entirety by reference to such Indenture (including the form of Notes attached thereto). A copy of the Supplemental Indenture is filed herewith as Exhibit 4.1 and is incorporated herein by reference.

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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.

Date: August 15, 2013

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