Well-defined polymers incorporated BODIPY dyes into the PMMA side chain, and the block copolymers were synthesized by the RAFT process. The controlled/living character of the polymerization of MMA monomers with pendant BODIPY dyes was confirmed by the formation of the narrow molecular weight distribution products, the linear first-order kinetic plot, linear increase of molecular weight with the conversion, and block extension with styrene. The SEM images of the obtained homopolymers showed micrometer-sized blubber particle- or chain-like structures, which come from the aggregated particles by strong intermolecular pi-pi stacking of BODIPY dyes. In contrast, the designed block copolymers formed nanoparticles with enhanced luminescence (Phi(F) > 0.70) by preventing higher molecular weight polystyrene segment from aggregation by the strong pi-pi stacking.