Herein, we report a rare example of cationic three-dimensional (3D) metal−organic framework (MOF) of [Cu5Cl3(TMPP)]Cl5•xSol (denoted as Cu-TMPP; H2TMPP = meso-tetrakis (6-methylpyridin-3-yl) porphyrin; xSol = encapsulated solvates) supported by [Cu8Cl6]10+ cluster secondary building units (SBUs) wherein the eight faces of the Cl−-based octahedron are capped by eight Cu2+. Surface-area analysis indicated that Cu-TMPP features a mesoporous structure and its solvate-like Cl− counterions can be exchanged by BF4−, PF6−, and NO3−. The polyvinylpyrrolidone (PVP) coated Cu-TMPP (denoted as Cu-TMPP-PVP) demonstrated good ROS generating ability, producing •OH in the absence of light (peroxidase-like activity) and 1O2 on light irradiation (650 nm; 25 mW cm−2). This work highlights the potential of Cu-TMPP as a functional carrier of anionic guests such as drugs, for the combination therapy of cancer and other diseases.