The intrinsic catalytic activity of cost-effective non-noble transition-metal-based electrocatalysts greatly limits their overall water splitting efficiency. In this work, Mo-/Ni-/Fe-based ternary transition-metal composites are uniformly anchored on the hierarchical nitrogen-doped carbon nanotubes (N-CNTs)/carbon cloth (CC) via a one-pot hydrothermal process, followed by hydrogenation and sulfurization to obtain the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalysts, respectively. The rationally designed hybrids with various crystalline structures, heteroatom dopants, and large accessible surface areas can form abundant heterojunction interfaces and rich active defects to adjust the local electronic structure and intrinsic electrocatalytic capability. Therefore, the H-MoNiFe/N-CNTs-2 electrode reveals a low OER overpotential of 259.0 mV at 50 mA cm −2 and a small Tafel slope of 44.3 mV dec −1 , while the S-MoNiFe/N-CNTs-1 electrode exhibits a good HER overpotential of 130.7 mV at 10 mA cm −2 . Moreover, the electrolysis device exhibits a low cell voltage of 1.58 V at 10 mA cm −2 and maintains excellent catalytic activity under a high current for 12 h. This work provides a simple but rational composite electrode construction strategy with broad application prospects for electrocatalytic reactions.