A major goal of aging research now is to find pharmacological manipulations in healthspan extension. Icariin is a flavonol isolated from medicinal herbal tonics. We have previously reported that icariin extended the healthspan of invertebrate models. Here, we showed that long-term treatment with icariin starting at 12months of age extended healthspan and mean lifespan in C57BL/6 mice. In all our assays associated with healthspan, such as behavioral tests and bone density analysis, we found that icariin boosted healthy features in mice. We also presented data indicating that such beneficial effects of icariin were due to at least two mechanisms: reduced oxidative stress indicated by the induction of antioxidant protein superoxide dismutase (SOD) activity and the decrease of oxidative marker malondialdehyde (MDA); maintained the genomic stability indicated by a reduction in DNA double-stranded breaks and down-regulation of DNA damage response genes. Our results indicated that icariin, a safe and widely used natural flavonol, extended healthspan and maintained genomic stability in a mammalian system.