Head rice yield (HRY) is a crucial quality trait that determines the final commodity yieldcommercial value of rice. Conversely, chalkiness represents an undesirable appearance characteristic, significantly impairing rice marketability. Thus, developing rice germplasms with superior HRYappearance traits is highly desirable for rice productionmarketing. However, the master modulesregulatory networks underlying HRYchalkiness remain largely unknown. Here, we demonstrate that the rice transcription factor OsMYB99 acts as a master regulator conferring high HRYlow chalkiness. Functional loss of OsMYB99 impairs cuticular wax biosynthesisdeposition in caryopsescauses accumulation of reactive oxygen species (ROS) in endosperms, consequently decreasing HRYincreasing chalkiness. Mechanistically, OsMYB99 functions as a transcription activator; it binds promoterspositively regulates the expression of wax biosynthesis gene OsGL1-4ROS scavenger OsMT2b. OsGL1-4 promotes cuticular wax biosynthesisdeposition in caryopses, while OsMT2b eliminates excess ROS in endosperms. Together, these actions lead to HRY enhancementchalkiness reduction. Our study uncovers the master regulator OsMYB99its molecular network modulating HRYchalkiness in rice, offering a strategy to improve these traits through modifying cuticular wax depositionROS production.