Initial Registration Statement for Employee Benefit Plan (Form S-8)

As filed with the Securities and Exchange Commission on November 3, 2026

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

IDEAYA Biosciences, Inc.

(Exact name of Registrant as specified in its charter)

IDEAYA Biosciences, Inc. 2023 Employment

Inducement Award Plan, as Amended

(Full Title of the Plan)

Yujiro Hata

President and Chief Executive Officer

IDEAYA Biosciences, Inc.

5000 Shoreline Court, Suite 300

South San Francisco, California 94080

(650) 443-6209

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Mark V. Roeder, Esq.

John C. Williams, Esq.

Latham & Watkins LLP

801 Jefferson Avenue, Suite 300

Redwood City, California 94063

(650) 328-4600

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company" and "emerging growth company" in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

PART I

INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

The information called for in Part I of Form S-8 is not being filed with or included in this Form S-8 (by incorporation by reference or otherwise) in accordance with the rules and regulations of the Securities and Exchange Commission (the "Commission").

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

In this Registration Statement, IDEAYA Biosciences, Inc. is sometimes referred to as "Registrant."

REGISTRATION OF ADDITIONAL SECURITIES

PURSUANT TO GENERAL INSTRUCTION E OF FORM S-8

This Registration Statement on Form S-8 (the "Registration Statement") is being filed with the Commission for the purpose of registering an additional 3,000,000 shares of common stock, par value $0.0001 per share ("common stock") of the Registrant issuable under the IDEAYA Biosciences, Inc. 2023 Employment Inducement Award Plan, as amended (the "Inducement Plan") pursuant to which the Registrant had previously reserved 4,000,000 shares of common stock. Shares available for issuance under the Inducement Plan were previously registered on registration statements on Form S-8 filed with the Commission on March 7, 2023 (File No. 333-270334), August 6, 2024 (File No. 333-281301), and August 5, 2025 (File No. 333-289256) (collectively, the "Prior Registration Statements"). The Prior Registration Statements are currently effective. This Registration Statement relates to securities of the same class as those to which the Prior Registration Statements relate. The Inducement Plan was adopted and amended by the Registrant's board of directors without stockholder approval pursuant to Nasdaq Listing Rule 5635(c)(4). Pursuant to General Instruction E of Form S-8, the contents of the Prior Registration Statements are incorporated by reference herein to the extent not modified or superseded hereby or by any subsequently filed document, which is incorporated by reference herein, except for Items 3 and 8, which are being updated by this Registration Statement.

Item 3. Incorporation of Documents by Reference.

The following documents previously filed by the Registrant with the Commission are incorporated by reference in this Registration Statement:

All documents that the Registrant subsequently files pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a post-effective amendment to this Registration Statement which indicates that all of the shares of common stock offered have been sold or which deregisters all of such shares then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be a part hereof from the date of the filing of such documents; except as to any portion of any future annual or quarterly report to stockholders or document or current report furnished under current Items 2.02 or 7.01 of Form 8-K, and exhibits furnished on such form that relate to such items, that is not deemed filed under such provisions. For the purposes of this Registration Statement, any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

Under no circumstances will any information filed under current Items 2.02 or 7.01 of Form 8-K, and exhibits furnished on such form that relate to such items, be deemed incorporated herein by reference unless such Form 8-K expressly provides to the contrary.

Item 8. Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in South San Francisco, California, on this 3rd day of November, 2026.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Yujiro Hata and Joshua Bleharski, Ph.D., and each of them acting individually, as his or her true and lawful attorneys-in-fact and agents, each with full power of substitution, for him or her in any and all capacities, to sign any and all amendments to this Registration Statement, including post-effective amendments, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Commission, granting unto said attorneys-in-fact and agents, with full power of each to act alone, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or his, her or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.