A cage hybrid (C-Cage–PB) was developed by electrostatic complexation of a quaternary ammonium cage (C-Cage⁺) and an anionic inorganic Prussian blue (PB⁻). Given the unique synergy of the two parts, such a cage hybrid can be used as a promising platform for the efficient removal of toxic compounds in wastewater through adsorption, delivery or catalytic degradation via a Fenton oxidation reaction. In addition, C-Cage–PB can encapsulate Pd clusters, which amplifies the function of the hybrid for enhanced catalytic performance in the sequential degradation of toxic organic compounds and heavy metal pollution in wastewater treatment.