In this study, a novel Mg-doped BaZrO 3 material with the perovskite structure was synthesized by solid-state reaction. Intense violet blue long-lasting phosphorescence (LLP) covering a wavelength range of 320–550nm was observed for BaZrO 3 :Mg 2+ for the first time, and this LLP wavelength range partially overlaps the absorption wavelength range of the commercial photocatalyst TiO 2 (P25). This overlap indicates that Mg-doped BaZrO 3 may assist the photocatalytic activity of TiO 2 . BaZrO 3 :Mg 2+ /TiO 2 composites were synthesized by a sol–gel method, and the subsequent characterization of these composites suggested that TiO 2 nanoparticles were successfully coated onto the surface of BaZrO 3 :Mg 2+ bulk particles. The ability of BaZrO 3 :Mg 2+ to assist the photocatalytic activity of TiO 2 was evaluated through investigations of the decomposition of methylene blue. The results revealed that the violet blue LLP of BaZrO 3 :Mg 2+ not only supports the photocatalytic activity of TiO 2 in the absence of UV light but also significantly increases the photocatalytic activity of per unit mass of TiO 2 under UV irradiation.