We herein report the synthesis of water‐soluble chitosan nanocomposites incorporating BODIPY, and the investigation of their photosensitization properties. It was observed that the singlet oxygen generation capability of nanocomposites containing a mixture of BODIPY and iodine‐containing molecules are higher than that of the nanocomposites containing BODIPY alone. We hypothesize that the supramolecular interactions between BODIPY and iodine‐containing molecules confined within the nanocomposites lead to the enhanced singlet oxygen generation.