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

I, Yujiro Hata, President and Chief Executive Officer of IDEAYA Biosciences, Inc. (the “Company”), hereby certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

(1)The Annual Report on Form 10-K of the Company for the period ended December 31, 2023 (the “Report”) fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; 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: February 20, 2024	By:	/s/ Yujiro Hata
		Yujiro Hata
		President and Chief Executive Officer
		(Principal Executive Officer)

I, Andres Ruiz Briseno, Senior Vice President and Head of Finance and Investor Relations of IDEAYA Biosciences, Inc. (the “Company”), hereby certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

(1)The Annual Report on Form 10-K of the Company for the period ended December 31, 2023 (the “Report”) fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; 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: February 20, 2024	By:	/s/ Andres Ruiz Briseno
		Andres Ruiz Briseno
		Senior Vice President and Head of Finance and Investor Relations
		(Principal Financial and Accounting Officer)