C-phycocyanin (C-PC), a natural biomaterial, is attracting attention for its unique photodynamic activity, anti- inflammatory and anti-cancer properties. To solve the problem of systemic distribution of photosensitizers, a nano- formulation strategy is essential. The aim of this study is to prepare chitosan-phycocyanin nanoparticles and evaluate their photodynamic therapeutic activity to confirm their potential as a photosensitizer. The average size of chitosan- phycocyanin nanoparticles was measured to be 308.02±3.29 nm and showed a spherical shape. In the DPBF evaluation, ?? it was confirmed that the chitosan-phycocyanin nanoparticles generated reactive oxygen species (ROS) under near infrared (NIR) laser irradiation, and the photodynamic activity of phycocyanin was maintained even after particle formation. Although no cytotoxicity was observed with chitosan-phycocyanin nanoparticles, it induced photodynamic therapy- mediated apoptosis in CT26 cells under NIR laser irradiation. All these results indicate that chitosan-phycocyanin nanoparticles could be attractive therapeutics for photodynamic therapy.