Heterogeneous photocatalysts have attracted extensive attention in photo‐induced electron transfer‐reversible addition–fragmentation chain transfer (PET‐RAFT) polymerization due to their remarkable advantages such as easy preparation, tunable photoelectric properties, and recyclability. In this study, zinc (II) 5,10,15,20‐tetrakis(4‐aminophenyl)porphyrin (ZnTAPP)‐based poly‐porphyrin nanoparticles (PTAPP‐Zn) are constructed by an emulsion‐directed approach. It is investigated as a heterogeneous photocatalyst for PET‐RAFT polymerization of various methacrylate monomers under visible light exposure, and the reactions show refined polymerization control with high monomer conversions. Furthermore, it is demonstrated that the PTAPP‐Zn nanoparticles with the larger pore size enhance photocatalytic activity in PET‐RAFT polymerization. In addition, the capabilities of oxygen tolerance and temporal control are demonstrated and PTAPP‐Zn particles can be easily recycled and reused without an obvious decrease in catalytic efficiency. [ABSTRACT FROM AUTHOR]