Designing and synthesizing high-activity, durable, and low-cost catalysts for the electrochemically transformation of water to hydrogen are vitally important to future energy systems. Herein, a simple but effective strategy for manganese-metal-heteroatom doping is adopted to intrinsically elevate the electrocatalytic activities of SnS2 nanosheets by a facile two steps hydrothermal-sulfurization approach. Electrocatalytic hydrogen evolution (HER) performance of Mn–SnS2 nanosheets grown on 3D nickel foam (Mn–SnS2/NF) is efficiently optimized since the dopants and defects endow the Mn–SnS2/NF vast active sites. An overpotential as low as 71 mV is required to drive a current density of 10 mA/cm2 with a low Tafel slope of 72 mV dec−1 in alkaline environment (1 M KOH). In addition, the Mn–SnS2/NF exhibits prominent stability in 1 M KOH electrolyte, which is an indispensable index for the potential HER electrocatalysts. The present work demonstrates that the heteroatom manganese doping strategy renders a meaningful route for synthesizing cost-efficient HER electrocatalysts in alkaline condition.