Simpson Thacher & Bartlett LLP

425 LEXINGTON AVENUE

NEW YORK, NY 10017-3954

TELEPHONE: +1-212-455-2000

FACSIMILE: +1-212-455-2502

July 2, 2018

KKR & Co. Inc.

9 West 57th Street

Suite 4200

New York, New York 10019

Ladies and Gentlemen:

We have acted as counsel to KKR & Co. Inc., a Delaware corporation (the “Company”), in connection with the Registration Statement on Form S-8 (File No. 333-223202), as amended by Post-Effective Amendment No. 1 (as amended, the “Registration Statement”), filed by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, relating to the issuance by the Company of an aggregate of up to 31,410,341 shares of Class A common stock of the Company, par value $0.01 (the “Shares”), pursuant to the Amended and Restated KKR & Co. Inc. 2010 Equity Incentive Plan (the “Plan”).

We have examined the Registration Statement and the Certificate of Incorporation of the Company and the Bylaws of the Company, which have been filed with the Commission as exhibits to the Registration Statement. We also have examined the originals, or duplicates or certified or conformed copies, of such records, agreements, documents and other instruments and have made such other investigations as we have deemed relevant and necessary in connection with the opinions hereinafter set forth. As to questions of fact material to this opinion, we have relied upon certificates or comparable documents of public officials and of officers and representatives of the Company.

In rendering the opinion set forth below, we have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as duplicates or certified or conformed copies and the authenticity of the originals of such latter documents.

Based upon the foregoing, and subject to the qualifications, assumptions and limitations stated herein, we are of the opinion that when the Shares registered under the Registration Statement are issued and delivered in accordance with the Plan, such Shares will be validly issued, fully paid and nonassessable.

We do not express any opinion herein concerning any law other than the Delaware General Corporation Law.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to Post-Effective Amendment No. 1 to the Registration Statement and to the use of our name under the caption “Interests of Named Experts and Counsel” contained in the Registration Statement.

	Very truly yours,

	/s/ Simpson Thacher & Bartlett LLP

	SIMPSON THACHER & BARTLETT LLP