Developing efficient bifunctional electrocatalyst for overall water splitting and conversion of biomass into value-added products at large current density is essential but challenging. Herein, a hierarchical Fe-doped Ni2P nanosheets hybridized with C on Ni foam (Fe-Ni2P@C/NF) was developed as a robust bifunctional catalyst with excellent catalytic activity for hydrogen evolution reaction (HER) with overpotentials of 75 and 313 mV at 10 and 1000 mA cm−2, respectively, and as well as for OER with a lower overpotential of 269 mV at 400 mA cm−2. Particularly, the integrated double-electrode electrolyzer for simultaneous HER and biomass-derived monosaccharide oxidation reaction (MOR) using Fe-Ni2P@C/NF only requires a low voltage of 1.55 V to drive a current density of 100 mA cm−2. Meanwhile, the value-added lactic acid is obtained at the anode. This strategy of coupling biomass oxidation to promote H2 production can significantly reduce energy consumption and obtain additional high value-added products.