In recent years, the antitumor application of photodynamic therapy (PDT) has gained widespread interest in treating solid tumors. Due to the hypoxic environment in tumors, the major limit of PDT seems to be the source of oxygen. In this work, we attempted to relieve hypoxia and enhance photodynamic therapy, and therefore, designed and assembled a catalytic cascade-enhanced PDT multifunctional nanoplatform. The mentioned platform termed UIO@Ca-Pt is based on porphyrinic metal-organic framework (UIO) combination, which is simultaneously loaded by CaO2 NPs with polydopamine (PDA) and then the Pt raw material to further improve biocompatibility and efficiency. In a tumor microenvironment, CaO2 could react with water to generate calcium hydroxide and hydrogen peroxide, which was further decomposed by Pt nanoparticles to form oxygen, thereby facilitating the generation of cytotoxic singlet oxygen by photosensitizer TCPP under laser irradiation. Both in vitro and in vivo experiment results confirmed the excellent oxygen production capacity and enhanced PDT effect of UIO@Ca-Pt. With guaranteed safety in PDT, the oxygen-supplying strategy might stimulate considerable interest in the development of various metal-organic materials with multifunctionality for tumor diagnosis and therapy.