Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Pliant Therapeutics, Inc. (the “Company”) on Form 10-K for the period ending December 31, 2022, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

(1)The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: March 9, 2023	/s/ Bernard Coulie
	Bernard Coulie, M.D., Ph.D.
	President and Chief Executive Officer
	(Principal Executive Officer)
	/s/ Keith Cummings
	Keith Cummings, M.D., MBA
	Chief Financial Officer
	(Principal Financial Officer)