Alkali metal ion intercalation into TiO2 photocatalysts is a well-known method for obtaining enhanced photo-catalytic properties. Herein, an effective electrochemical lithiation method is proposed for the synthesis of lithium-intercalated TiO2 nanoparticles (NPs) suitable for high performance photocatalytic production of hydrogen. The electrochemical lithiation of TiO2 induces partial reduction of Ti ions in the crystal lattices, which introduces additional energy states within the band edge of TiO2, resulting in the improved optical properties. Consequently, Li-intercalated TiO2 NPs exhibit almost 60-times improved hydrogen generation activity under both UV and visible light exposure compared to those of commercial TiO2 NPs (P25).