UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

For the fiscal year ended December 31, 2015

OR

For the transition period from                      to                     

Commission file number 001-36835

Columbia Pipeline Partners LP

(Exact name of registrant as specified in its charter)

(713) 386-3701

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ¨    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act.    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in of this Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definition of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12-b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).    Yes  ¨    No  x

The aggregate market value of Common Units (based upon the June 30, 2015, closing price of $25.20 on the New York Stock Exchange) held by non-affiliates was approximately $1,353,717,666.

At April 6, 2016, there were 53,834,784 Common Units and 46,811,398 Subordinated Units outstanding.

EXPLANATORY NOTE

This Amendment No. 1 (“Amendment”) to the Annual Report on Form 10-K of Columbia Pipeline Partners LP (“CPPL” or the “Partnership”) for the fiscal year ended December 31, 2015, as filed with the Securities and Exchange Commission (“SEC”) on February 18, 2016 (the “Original Form 10-K”), is being filed for the purpose of amending Item 11 of Part III.

On March 17, 2016, Columbia Pipeline Group, Inc., a Delaware corporation and the indirect parent company of the Partnership (“CPG”), entered into an Agreement and Plan of Merger (the “Merger Agreement”), among CPG, TransCanada PipeLines Limited, a Canadian corporation (“Parent”), TransCanada PipeLine USA Ltd., a Nevada corporation and a wholly owned subsidiary of Parent (“US Parent”), Taurus Merger Sub Inc., a Delaware corporation and a wholly owned subsidiary of US Parent (“Merger Sub”), and, solely for purposes of Section 3.02, Section 5.02, Section 5.09 and Article VIII of the Merger Agreement, TransCanada Corporation, a Canadian corporation and the direct parent company of Parent (“Ultimate Parent”). Upon the terms and subject to the conditions set forth in the Merger Agreement, Merger Sub will be merged with and into CPG (the “Merger”) with CPG surviving the merger as an indirect wholly owned subsidiary of Ultimate Parent.

As a result of the proposed Merger, CPG no longer expects to hold a 2016 annual meeting of stockholders, and therefore does not intend to file a definitive proxy statement in connection therewith in 2016. As a result, CPPL is filing this Amendment to refer readers to certain information that will be included in CPG’s amended Annual Report on Form 10-K for the fiscal year ended December 31, 2015.

As required by the rules of the SEC, this Amendment sets forth an amended “Item 15. Exhibits and Financial Statement Schedules” in its entirety and includes the new certifications from the Partnership’s chief executive officer and chief financial officer. Because no financial statements or financial information have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted.

Except as otherwise stated herein, no other information contained in the Original Form 10-K has been updated by this Amendment. This Amendment should be read in conjunction with our periodic filings made with the SEC, subsequent to the date of the Original Form 10-K.

2

PART III

ITEM 11. EXECUTIVE COMPENSATION

Our Chairman and Chief Executive Officer, Robert C. Skaggs, Jr., President, Glen L. Kettering, Executive Vice President and Chief Financial Officer, Stephen P. Smith, Executive Vice President and Chief Commercial Officer, Stanley G. Chapman, III, and Executive Vice President and Chief Operations Officer, Shawn L. Patterson, are our “Named Executive Officers.” Our Named Executive Officers are also the Named Executive Officers of CPG. We do not directly employ our Named Executive Officers for managing our business, and we do not have a compensation committee. We are managed by our general partner, and our Named Executive Officers are employees of CPG. Our Named Executive Officers are compensated directly by CPG. All decisions as to the compensation of our Named Executive Officers are and will be determined and approved by the compensation committee of CPG. Therefore, we do not have any policies or programs relating to compensation of our Named Executive Officers, and we make no decisions relating to such compensation. We have no control over this compensation determination process. The Named Executive Officers of CPG participate in CPG’s employee benefit plans and arrangements, including any CPG plans that may be established in the future.

We reimburse our sponsor for the services provided to us by our sponsor’s employees, including our Named Executive Officers. Our reimbursement is governed by our omnibus agreement and will be based on our sponsor’s methodology used for allocating compensation expenses to us. None of the Named Executive Officers of CPG have employment agreements with us or are otherwise specifically compensated by us for their service as a Named Executive Officer of CPG. Other than any awards that may be granted in the future under our long-term incentive plan, the compensation of our Named Executive Officers currently is, and in the future will be, determined and approved by CPG. We are solely responsible for paying the expense associated with any awards granted under our long-term incentive plan.

A full discussion of the policies and programs of the compensation committee of CPG is set forth in Amendment No. 1 to CPG’s Annual Report on Form 10-K for the fiscal year ended December 31, 2015, which is available on the SEC’s website at www.sec.gov and on CPG’s website at www.cpg.com under the “Investors” tab.

Long-Term Incentive Plan

In connection with our initial public offering, our general partner adopted the Columbia Pipeline Partners LP Long-Term Incentive Plan (“LTIP”). The LTIP provides our general partner with maximum flexibility with respect to the design of compensatory arrangements for employees, officers, consultants, and directors of our general partner and any of its affiliates providing services to us. However, except with respect to phantom units granted in connection with retainers provided to our non-employee directors, as described below under “Compensation of Directors,” to date we have not made any grants of awards pursuant to the LTIP.

Compensation Committee Report

Neither we nor our general partner has a compensation committee. The board of directors of our general partner has reviewed and discussed with management the Compensation Discussion and Analysis contained in this report, and based on these reviews and discussions, recommended that the Compensation Discussion and Analysis be included in this report.

The board of directors of CPP GP LLC:

Robert C. Skaggs, Jr.

Stephen P. Smith

Glen L. Kettering

Robert E. Smith

Stanley G. Chapman, III

Thomas W. Hofmann

G. Stephen Finley

Peggy A. Heeg

Compensation of Directors

Officers or employees of CPG or its affiliates who also serve as directors of our general partner do not receive additional compensation as such.

Our general partner has implemented an annual retainer compensation package for our non-employee directors valued at approximately $150,000 (pro-rated for partial years), of which approximately $60,000 will be paid in the form of an annual cash retainer and the remaining $90,000 retainer fee will be paid in a grant of phantom unit awards under the LTIP.

3

In addition, our general partner has approved an additional cash retainer for our audit committee chairman in an annual amount of $20,000.

In addition, each non-employee director will be reimbursed for out-of-pocket expenses in connection with attending board and committee meetings. Each director will be fully indemnified by us for actions associated with being a director to the fullest extent permitted under Delaware law pursuant to our partnership agreement.

The following table discloses the cash, equity awards and other compensation earned, paid or awarded, to each of our directors during 2015.

4

PART IV

ITEM 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

Financial Statements and Financial Statement Schedules

The financial statements and financial statement schedules listed in the Index to consolidated financial statements were filed as part of the Original Form 10-K.

Exhibits

See Index to Exhibits on page 7 of this Amendment.

These exhibits are filed with or incorporated by reference in this Amendment.

5

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this Amendment No. 1 of Form 10-K/A to be signed on its behalf by the undersigned, hereunto duly authorized.

6

EXHIBIT INDEX

The following exhibits listed below are filed with or incorporated by reference in this Amendment No. 1 to Form 10-K/A. Exhibits designated by an asterisk (*) are filed herewith and those designated with asterisks (**) are furnished herewith; all exhibits not so designated are incorporated herein by reference to a prior filing as indicated. Exhibits designated with (†) are management contracts or compensatory plan or agreement of Columbia Pipeline Partners LP.

7

8