A black phosphorus (BP)-based drug delivery system for synergistic photodynamic/photothermal/chemotherapy of cancer is constructed. As a 2D nanosheet, BP shows super high drug loading capacity and pH-/photoresponsive drug release. The intrinsic photothermal and photodynamic effects of BP enhance the antitumor activities. The synergistic photodynamic/photothermal/chemotherapy makes BP-based drug delivery system a multifunctional nanomedicine platform.