Multi-structure assemblies consisting of gold nanoparticles and porphyrin were fabricated by using diblock copolymer, poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP). The copolymer of PEG-b-P4VP was used in the formation of core-shell micelles in water, in which the P4VP block serves as the core, while the PEG block forms the shell. In the micellar core, gold nanoparticle and metalloporphyrin were dispersed through the axial coordination. Structural and morphological characterizations of the complex micelle were carried out by transmission electron microscopy, laser light scatting, and UV-visible spectroscopy. Metalloporphyrin in the complex micelle exhibited excellent photostability by reducing the generation of the singlet oxygen. This strategy may provide a novel approach to design photocatalysts that have target applications in photocatalysis and solar cells.