A novel effective 0D/3D nanohybrids of Mn0.05Cd0.95S/NiSe2 photocatalysts, which are formed by Mn0.05Cd0.95S nanoparticles anchored on the outer surface of cubic NiSe2 in designed and prepared. The optimum hydrogen evolution rate of the Mn0.05Cd0.95S/NiSe2 composite is 14.3 mmol h-1 g-1, which is 7.5 times higher than that of single Mn0.05Cd0.95S. Structural analyses and experimental results reveal that a little amount of NiSe2 can remarkably improve the photocatalytic activity and the close contact of the 0D/3D composite catalyst also plays an important role. Furthermore, NiSe2 can not only as both an electron acceptor to capture electrons and inhibit the recombination of electron-hole pairs, but also provide sufficient active sites to facilitate the photocatalytic water-splitting reaction activity. This work demonstrates that low-cost NiSe2 is a promising co-catalyst for photocatalytic splitting of water to produce hydrogen.