Aging, a process of functional decline with the increase of chronological age, is a major risk factor for chronic diseases. Aging shows significant individual differences, which is influenced by both genetic and environmental factors. Accurate measurement of physiological age helps identify individuals with accelerated aging and those at high risk for chronic diseases and mortality, which would promote individual health management and precision medicine for healthy aging. In this paper, we summarize the omics-based aging clocks and discuss their current and future applications.