Circadian clocks regulate growth and development in plants and animals, but the role of circadian regulation in crop production is poorly understood. Rice ( ) grain yield is largely determined by tillering, which is mediated by physiological and genetic factors. Here we report a regulatory loop that involves the circadian clock, sugar, and strigolactone (SL) pathway to regulate rice tiller-bud and panicle development. Rice ( ) positively regulates expression of ( , also known as ), ( ), and ( , also known as ) to repress tiller-bud outgrowth. Downregulating and overexpressing increases and reduces tiller numbers, respectively, whereas manipulating ( ) expression results in the opposite effects. also regulates expression to mediate panicle and grain development. Genetic analyses using double mutants and overexpression in the mutants show that , , and act downstream of Sugars repress expression in roots and tiller buds to promote tiller-bud outgrowth. The circadian clock integrates sugar responses and the SL pathway to regulate tiller and panicle development, providing insights into improving plant architecture and yield in rice and other cereal crops.