CAT and neoplasm: In summary, for the first time, Cu‐doped PPy nanozymes containing mixed valance states (CuI/CuII) were successfully constructed by a straightforward one‐step procedure using CuCl2 as oxidizing catalysts, which possessed trienzyme‐like activities, including CAT, POD, and GPx, to specifically promote O2 and ·OH elevation but GSH reduction in TME, thus causing irreversible oxidative stress damage to tumor cells and reversing the redox balance.