The pursuit of single‐assembled molecular cage reactors for complex tandem reactions is a long‐standing target in biomimetic catalysis but still a grand challenge. Herein, nanozyme‐like organic cages are reported by engineering air‐stable radicals into the skeleton upon photoinduced electron transfer. The generation of radicals is accompanied by single‐crystal structural transformation and exhibits superior stability over six months in air. Impressively, the radicals throughout the cage skeleton can mimic the peroxidase of natural enzymes to decompose H2O2 into OH· and facilitate oxidation reactions. Furthermore, an integrated catalyst by encapsulating Au clusters (glucose oxidase mimics) into the cage has been developed, in which the dual active sites (Au cluster and radical) are spatially isolated and can work as cascade nanozymes to prominently promote the enzyme‐like tandem reaction via a substrate channeling effect. A tandem reaction with an enhanced rate is achieved by an air‐stable radical cage reactor, in which the dual active sites (radicals as peroxidase mimics; Au clusters as glucose oxidase mimics) are spatially isolated without mutually quenching each other, and can thus serve as cascade nanozymes to accelerate the reaction via a substrate channeling effect.