Cellular senescence is a cell fate triggered by inherent or environmental stress and characterized by stable cell cycle arrest accompanied by a hypersecretory feature, termed as the senescence-associated secretory phenotype (SASP). Senescent cell burden increases with natural aging, functionally contributing to age-related organ dysfunction and multiple disorders. In this study, we performed a large scale screening of a natural product library for senotherapeutic candidates by assessing their effects on human senescent cells. Apigenin, a dietary flavonoid previously reported with antioxidant and anti-inflammatory activities, exhibited a prominent capacity in targeting senescent cells as a senomorphic agent. In senescent cells, apigenin blocks the interactions between ATM/p38 and HSPA8, thus preventing transition of the acute stress-associated phenotype (ASAP) towards the SASP. Mechanistically, apigenin targets peroxiredoxin 6 (PRDX6), an intracellular redox-active molecule, suppressing the iPLA2 activity of PRDX6 and disrupting downstream reactions underlying the SASP development. Without reversing cellular senescence, apigenin deprives cancer cells of malignancy acquired from senescent stromal cells in culture, while reducing chemoresistance upon combination with chemotherapy in anticancer regimens. In preclinical trials, apigenin administration improves physical function of animals prematurely aged after whole body irradiation, alleviating physical frailty and cognitive impairment. Overall, our study demonstrates the potential of exploiting a naturally derived compound with senomorphic capacity to achieve geroprotective effects by modulating the SASP, thus providing a research platform for future exploration of novel natural agents against age-related conditions.