Exhibit 32.1

CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER PURSUANT TO 18 U.S.C. § 1350, AS ADOPTED PURSUANT TO SECTION 906OF THE SARBANES­OXLEY ACT OF 2002

I, Patrick Soon-Shiong, the chief executive officer of NantKwest, Inc. (the “Company”), certify for the purposes of 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

i. the Quarterly Report of the Company on Form 10-Q for the quarter ended March 31, 2018 (the “Report”), fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

ii. the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 7, 2018	By:	/s/ Patrick Soon-Shiong
		Patrick Soon-Shiong
		Chief Executive Officer