Exhibit 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (No. 333-173025, 333-162885, 333-139562 and 333-109296) of Merck & Co., Inc. of our report dated June 17, 2016, relating to the financial statements of the MSD Employee Stock Purchase and Savings Plan, which appears in this Form 11-K.

/s/ PricewaterhouseCoopers LLP

New York, New York

June 17, 2016

- 15 -