The hydrogen evolution reaction in an alkaline environment using a non-precious catalyst with much greater efficiency represents a critical challenge in research. Here, a robust and highly active system for hydrogen evolution reaction in alkaline solution is reported by developing MoS2 nanosheet arrays vertically aligned on graphene-mediated 3D Ni networks. The catalytic activity of the 3D MoS2 nanostructures is found to increase by 2 orders of magnitude as compared to the Ni networks without MoS2. The MoS2 nanosheets vertically grow on the surface of graphene by employing tetrakis(diethylaminodithiocarbomato)molybdate(IV) as the molybdenum and sulfur source in a chemical vapor deposition process. The few-layer MoS2 nanosheets on 3D graphene/nickel structure can maximize the exposure of their edge sites at the atomic scale and present a superior catalysis activity for hydrogen production. In addition, the backbone structure facilitates as an excellent electrode for charge transport. This precious-metal-free and highly efficient active system enables prospective opportunities for using alkaline solution in industrial applications.