Developing catalysts both efficient and cost-effective is vital to achieve sustainable hydrogen production in water electrolysis process. Here, we propose a facile strategy to fabricate Ni@Ni(OH)₂ heterostructure catalyst on Ti paper substrate combining electrodeposition and subsequent electrochemical activation process. Detail characterization revealed that Ni (oxy)hydroxides generated and the Ni@Ni(OH)₂ underwent surface reconstruction with formation of abundant heterojunctions and electron modulation during the electrochemical activation process, substantially increasing the exposed edges for the adsorption of intermediates during hydrogen evolution reaction (HER) process. Thus, the resulted Ni@Ni(OH)₂ /Ti electrode after the activation exhibited a much improved high HER activity in the half cell test, reaching the current density of −10 mA/cm² at an overpotential of 58 mV with Tafel slope of 83 mV/dec. Furthermore, an anion exchange membrane water electrolyzer applying the Ni@Ni(OH)₂/Ti cathode and commercial IrO₂/CP anode demonstrated current density up to 1.00 A/cm² at 2.0 V_cell and even showed superior performance than Pt/C at high current density region above 2.0 A/cm².