Light has been widely utilized in cancer therapies. In photodynamic therapy, cancer cells are killed by toxic reactive oxygen species (ROS) released by photosensitizers upon light irradiation. Nanostructures composed of gold-semiconductor are promising photosensitizers due to their strong absorption and high chemical stability compared with traditional organic photosensitizers. Nevertheless, the high cost and complex shape design of gold are two major concerns. Here, we replace gold with titanium nitride (TiN), and synthesize TiN@TiO2 core-shell nanoparticles for photodynamic therapy. No further shape design is required for TiN as its optical resonance naturally sits in the near infra-red wavelength range. Excitation of TiN@TiO2 nanoparticles by a 700 nm laser effectively produces ROS, driven primarily by hot electron transfer. Considering the chemical inertness, biocompatibility and low cost of TiN, TiN@TiO2 nanoparticles hold great potential as practical photosensitizers for photodynamic therapy.