In overall water splitting, oxygen evolution reaction is a rate-determining step due to its complex reaction processes with sluggish kinetics, so design of bifunctional electrocatalyst with elaborated structure to improve the oxygen evolution reaction performance is critical to their efficient application in overall water splitting. Here bifunctional CoMoS4/Ni3S2 nanostructures are in situ synthesized by a self-templating strategy, and the morphology control of the CoMoS4 outlayer is simultaneously achieved through a unique evolution from CoMoO4 nanocolumns array to hollow CoMoS4 nanosheets array with porous structure. Benefited from the synergistic effect of Ni3S2 interlayer, as obtained electrode exhibits greatly enhanced oxygen evolution activity than single CoMoS4 electrode with well-preserved hydrogen evolution activity. It, together with the three-dimensional topographic structure of CoMoS4 outlayer with high active areas, offers a rather low cell voltage (1.568 V@ 10 mA cm(-2)) for overall water splitting in a two-electrode system. Accordingly, our results may open new opportunities to explore hybrid nanostructures as efficient bifunctional electrocatalyst for overall water splitting.