We report a photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) dispersion polymerization mediated by 5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP) under low energy red (lambda(max) = 635 nm) or yellow light (lambda(max) = 560 nm). By varying the degrees of polymerization for the hydrophobic block, nanoparticles of different morphologies (spheres, wormlike micelles, and vesicles) were formed at high monomer conversion (>98%) under visible light irradiation. Interestingly, encapsulation of the ZnTPP catalyst into the nanoparticle core was achieved by direct dialysis against water with no significant change in nanoparticle morphology. These aqueous ZnTPP-loaded nanoparticles were demonstrated to have potential applications in photodynamic therapy owing their ability to generate singlet oxygen under visible light irradiation. Finally, the ability of ZnTPP to generate singlet oxygen was exploited to perform polymerization without traditional deoxygenation procedures by addition of a singlet oxygen quencher (ascorbic acid).