Engineering multifunctional nanoplatforms with high therapeutic benefits has become a promising strategy for intractable cancer treatment. A novel polyphenol-based nanocomplex was designed to evoke highly efficacious cancer immunosurveillance while localizing therapy on the primary tumor and to minimize systemic side effects. This nanocomplex is prepared via metal–polyphenol coordination by encapsulating a natural polyphenol, gossypol, and a newly synthesized polyphenol derivative, polyethylene glycol-Chlorin e6 (Ce6). The combination of gossypol from cotton and the photosensitizer Ce6 can induce chemotherapeutic/photodynamic immunogenic cancer cell death upon laser irradiation, which is supported by a rich maturation of dendritic cells, concentrated secretion of inflammatory cytokines, and significant inhibition of distant untreated tumors. Finally, an assistance of the programmed-cell-death ligand-1 checkpoint-blockade immunotherapy can enhance the anti-tumor immune stimulation of our nanoplatform to a higher level.