In this study, we have fabricated crystalline metallic Pt nanoparticles-loaded α-Bi₂O₃ microrods (Pt/Bi₂O₃) using a precipitation method, followed by an impregnation–reduction deposition route. The Pt/Bi₂O₃ catalysts have much higher photocatalytic activities than that of the pure Bi₂O₃ for the degradation of RhB and 2,4-DCP under visible light irradiation. The photogenerated charge separation, transfer, and capture in the photocatalysis of Pt/Bi₂O₃ were investigated in detail according to the various characterizations and analyses of the photogenerated active species and H₂O₂. It was revealed that the loaded Pt plays an important mediating role in the efficient separation of photogenerated electron–hole pairs by rapidly transferring electrons from the excited Bi₂O₃ to the surface oxygen. As a result, the reduction of O₂ to form H₂O₂ by the photogenerated electrons was promoted, leaving more holes on the deep valence band to drive the degradation of organic compounds and the production of ˙OH radicals, which were responsible for the enhanced photocatalysis of Pt/Bi₂O₃.