The search for antiaging drugs is a key component of gerontology research. A few drugs with positive effects on life span in model organisms have been found. Here, we report that 2,5-dimethyl-celecoxib, a derivative of the anti-inflammatory drug celecoxib, can extend Drosophila life span and delay aging by a mechanism involving insulin signaling and target of rapamycin signaling. Importantly, its positive effects were apparent when the treatment window was restricted to the beginning of life or the later half. 2,5-Dimethyl-celecoxib-induced longevity was also associated with improvements in physical activity, intestinal integrity, and increased autophagy. In addition, 2,5-dimethyl-celecoxib exhibited protective effects against several kinds of stress such as starvation and heat. The generally positive effects of 2,5-dimethyl-celecoxib on both health and life span, combined with its mode of action via evolutionarily conserved signaling pathways, indicate that it has the potential to become an effective antiaging drug.