Developing novel hydrogen evolution reaction (HER) catalysts with high activity, high stability and low cost is of great importance for the ever-broader applications of hydrogen energy. Among the conventionally used platinum-based heterogeneous catalysts, the high consumption and low utilization efficiency of precious platinum are the most crucial issues. Herein we present a facile approach to prepare an effective HER catalyst with platinum nanoparticles dispersed on oxygen-deficient TiO_2−x nanosheets (NSs). The fabricated Pt–TiO_2−x NS electrocatalyst shows an overpotential of 35 mV at 10 mA cm⁻² for the HER in 0.5 M H₂SO₄, which is highly comparable to that of commercial Pt/C (34 mV). More attractively, the Pt–TiO_2−x NS electrocatalyst largely enhanced the mass activity (MA) of Pt and electrochemical stability compared to commercial Pt/C. The excellent HER performance of Pt–TiO_2−x NSs is attributed to the synergetic effect between highly dispersed Pt species and TiO_2−x NSs with oxygen vacancies, which enhances both electrocatalytic activity and durability over a wide pH range. This strategy can provide insights into constructing highly efficient catalysts and their support for different energy-related applications.