X0206 3 2023-11-06 0 0001845337 Day One Biopharmaceuticals, Inc. DAWN 0001744507 Dubow Adam 2000 SIERRA POINT PARKWAY, SUITE 501 BRISBANE CA 94005 0 1 0 0 General Counsel Common Stock 3141 D Stock Option (Right to Buy) 21.14 2032-10-30 Common Stock 309000 D Stock Option (Right to Buy) 23.41 2033-01-16 Common Stock 90000 D Restricted Stock Units Common Stock 47400 D Restricted Stock Units Common Stock 22750 D The option vests as to 25% of the total shares on October 31, 2023, and then 1/48th of the total shares vest monthly thereafter, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 1/48th of the total shares monthly, commencing February 17, 2023, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The Restricted Stock Units ("RSUs") vest as to 25% of the total award on November 15, 2023, and 1/12th of the remaining amount vests in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock upon settlement for no consideration. The RSUs will vest as to 1/16th of the total award in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date. Exhibit 24 - Power of Attorney /s/ Charles N. York II, Attorney-in-Fact 2023-11-16