In this work, a facile method is used to fabricate Cu-mediated NiFe-LDH (CuNiFe-LDH) nanoprisms from conductive metal–organic frameworks (MOFs; NiFe MIL-88A). The initial MOF structure is stabilized by electronic coupling and Cu ion coordination. The CuNiFe-LDH nanoprisms exhibit excellent OER performance, with an overvoltage of 204 mV at a current density of 10 mA cm−2 and a low activation energy of 15.45 kJ mol−1. Mechanistic investigations using density functional theory calculations demonstrate that the Cu sites in CuNiFe-LDH are highly efficient for OER and that CuNiFe-LDH has a lower theoretical overpotential than NiFe-LDH. A wireless photovoltaic-electrochemical cell, developed using a CuNiFe-LDH/Ni fiber paper (NFP) anode and NiFe2O4/NFPcathode, achieves a solar-to-hydrogen efficiency of 11.08%. Additionally, the excellent performance of anion exchange membrane water electrolyzer incorporating the CuNiFe-LDH catalyst, including a j of 974 mA cm−2 at 1.85 V, and 46.9 kWh of electricity consumed per 1 kg of hydrogen produced.