Integrating　the　hydrogen　evolution　reaction　(HER)　and　urea　oxidation　reaction　(UOR)　is　an　energy-saving　approach　for　electrolytic　H2　production.　Here,　hollow　NiCoP　nanoprisms　are　derived　from　Prussian　blue　analogues　by　a　combined　self-template　coordination　reaction　and　gas-phase　phosphorization　strategy.　Benefiting　from　the　strong　electron　interaction,　unique　hollow　nanostructure,　and　enhanced　mass/charge　transfer,　NiCoP　nanoprisms　display　outstanding　alkaline　HER　and　UOR　performance.　Specifically,　low　potentials　of　−0.052,　−0.115,　and　−0.159 V　for　HER　and　ultralow　potentials　of　1.30,　1.36,　and　1.42 V　for　UOR　at　current　densities　of　10,　50,　and　100 mA　cm−2　are　obtained.　Moreover,　in　a　urea-assisted　water　electrolysis　system,　NiCoP　nanoprisms　only　require　cell　voltages　of　1.36,　1.49,　and　1.57 V　to　offer　current　densities　of　10,　50,　and　100 mA　cm−2,　about　170,　180,　and　200 mV　less　than　the　traditional　water　electrolysis.　Theoretical　calculations　indicate　the　Co　substitution　in　Ni2P　promotes　the　adsorption　and　dissociation　of　water　molecules,　optimizes　the　desorption　energy　of　active　hydrogen　atoms,　and　enhances　the　adsorption　of　urea　molecules,　thus　accelerating　the　kinetics　of　HER　and　UOR.　This　work　facilitates　the　application　of　hollow　bimetallic　phosphides　in　electrochemical　preparation　of　clean　energy　and　provides　a　successful　paradigm　for　urea-rich　wastewater　electrolysis.　©　2022　Wiley-VCH　GmbH.