Tripartite prodrug 1, composed of an NAD(P)H:quinone oxidoreductase 1 (NQO1)-responsive trigger group, a self-immolative linker, and the active drug 5-fluorouracil (5-FU), was designed and synthesized for site-specific cancer therapy. Upon bioreductive activation by NQO1, 1 can release the parent drug 5-FU specifically in NQO1-overexpressing cancer cells. This prodrug exerts comparable antitumor activity and a more favorable safety profile compared with 5-FU both in vitro and in vivo.