Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report dated February 27, 2015 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in MPLX LP’s Annual Report on Form 10-K for the year ended December 31, 2014. We also consent to the reference to us under the heading “Experts” in such Registration Statement.

/s/  PricewaterhouseCoopers LLP

Toledo, Ohio

March 27, 2015