A single electrochemical cell integrating hydrogen oxidation reaction (HOR) with carbon dioxide reduction reaction (CO₂RR) is presented, which significantly reduces energy loss and enhances efficiency. The cell uses a Ni(OH)₂/NiOOH mediator to suppress anodic carbon loss and HOR catalyst poisoning by migrated reaction products. This cell can produce either gaseous (CO) or soluble (formate) products with high selectivity (up to 95.3%) and stability (>100 h) at voltages below 0.9 V (50 mA cm⁻²). The integration of hydrogen with CO₂RR transfers the oxygen evolution reaction (OER) to a water electrolyzer, reducing total polarization loss and energy consumption by up to 22% and 42%, respectively. This approach demonstrates the potential for combining CO₂ electrolysis with the hydrogen economy, paving the way for improved energy/cost effectiveness through integrated energy conversion and storage methods. The cell design includes a gradient functional layer to minimize cathodic overpotential loss and a gas-diffusion electrode for efficient product transport. The study also evaluates the performance of different catalysts and electrodes, showing that the Ni(OH)₂/NiOOH mediator offers significant kinetic advantages over conventional systems. The cell demonstrates high voltage efficiency and stability, with a Coulombic efficiency of over 99%. The integration of hydrogen with CO₂RR not only reduces energy consumption but also addresses challenges related to product crossover and catalyst poisoning. The study highlights the potential of this approach for sustainable energy production and storage.A single electrochemical cell integrating hydrogen oxidation reaction (HOR) with carbon dioxide reduction reaction (CO₂RR) is presented, which significantly reduces energy loss and enhances efficiency. The cell uses a Ni(OH)₂/NiOOH mediator to suppress anodic carbon loss and HOR catalyst poisoning by migrated reaction products. This cell can produce either gaseous (CO) or soluble (formate) products with high selectivity (up to 95.3%) and stability (>100 h) at voltages below 0.9 V (50 mA cm⁻²). The integration of hydrogen with CO₂RR transfers the oxygen evolution reaction (OER) to a water electrolyzer, reducing total polarization loss and energy consumption by up to 22% and 42%, respectively. This approach demonstrates the potential for combining CO₂ electrolysis with the hydrogen economy, paving the way for improved energy/cost effectiveness through integrated energy conversion and storage methods. The cell design includes a gradient functional layer to minimize cathodic overpotential loss and a gas-diffusion electrode for efficient product transport. The study also evaluates the performance of different catalysts and electrodes, showing that the Ni(OH)₂/NiOOH mediator offers significant kinetic advantages over conventional systems. The cell demonstrates high voltage efficiency and stability, with a Coulombic efficiency of over 99%. The integration of hydrogen with CO₂RR not only reduces energy consumption but also addresses challenges related to product crossover and catalyst poisoning. The study highlights the potential of this approach for sustainable energy production and storage.