The high intermediate (H*, OH*) energy barriers and slow mass/charge transfer increase the overpotential of alkaline water electrolysis at large‐current‐density. Engineering the electronic structure with the morphology of the catalyst to reduce energy barriers and improve mass/charge transportation is effective but remains challenging. Herein, a Ce‐doped CoP nanosheet is hybrid with Ni3P@NF (Ni foam) support to enhance mass/charge transfer, tune energy barriers, and improve water‐splitting kinetics through a synergistic activation. The engineered Ce0.2‐CoP/Ni3P@NF cathode exhibits an ultralow overpotential (η500, η1000) of −185, and −225 mV at −500 and −1000 mA cm−2 in 1.0 m KOH, along with an excellent pH‐universality. Impressively, an electrolyzer using the Ce0.2‐CoP/Ni3P@NF cathode can afford 500 mA cm−2 at a cell voltage of only 1.775 V and maintain stable electrolysis for 200 h in 25 wt% KOH (50 °C). Characterization and density functional theory calculation further reveal the Ce‐doping and CoP/Ni3P hybrid interaction synergistically downshift d‐band centers (εd = −2.0 eV) of Ce0.2‐CoP/Ni3P to the Fermi level, thereby activate local electronic structure for accelerating H2O dissociation and optimizing Gibbs free energy of hydrogen adsorption (∆GH*). A highly efficient Ce0.2‐CoP/Ni3P@NF cathode is designed with a synergistic activation strategy. The Ce‐doping and CoP/Ni3P hybrid interactions synergistically enhance charge/mass transfer, engineering the local electronic structure to reduce energy barriers. Therefore, the Ce0.2‐CoP/Ni3P@NF exhibits an ultralow overpotential of 185 mV, 162 mV, 406 mV at −500 mA cm−2 in 1.0 m KOH, 0.5 m H2SO4, and 1.0 m PBS.