Abstract: Circadian rhythm exerts an important regulatory effect on the physiology, metabolism, and behavior of organisms. The formation of circadian rhythms results from the process of body adapting to the earthly environment during evolution and therefore forms autonomous oscillatory patterns following the cycle of earth rotation. Many studies have revealed that the transcription and expression of key genes in physiological processes, such as cell proliferation and cell metabolism, were regulated by circadian genes. This kind of regulation also plays a key role in the pathophysiology of cells, such as tumorigenesis. This review discusses the interconnections and molecular mechanisms between circadian rhythms and the process of cancer genesis, progression, and treatment, and provide a critical "clock" basis for developing personalized and precise cancer therapeutic strategies based on circadian rhythms.