The preparation of efficient and low‐cost bifunctional catalysts with superior stability for water splitting is a topic of significant current interest for hydrogen generation. A facile strategy has been developed to fabricate highly active electrodes with hierarchical porous structures by using a two‐step electrodeposition method, in which NiFe layered double hydroxide is grown in situ on a three‐dimensional hierarchical Ni mesh (NiFe/Ni/Ni). The as‐prepared NiFe/Ni/Ni electrodes demonstrate remarkable structural stability with high surface areas, effective gas transportation, and fast electron transfer. Benefiting from the unique structure, the self‐supported NiFe/Ni/Ni electrodes exhibit overpotentials of 190 mV and 300 mV for the oxygen evolution reaction (OER) at current densities of 10 and 500 mA cm−2, respectively. Furthermore, the self‐supported NiFe/Ni/Ni electrodes also exhibit high performance in the hydrogen evolution reaction (HER) and excellent stability at a current density of 500 mA cm−2 for both OER and HER. Remarkably, using NiFe/Ni/Ni as both the cathode and anode for alkaline water electrolysis, a current density of 500 mA cm−2 is attained at a cell voltage of 1.96 V. Additionally, the water electrolyzer demonstrates superior stability even at a large current density (500 mA cm−2) when subjected to high temperatures. Nickel all the way down: NiFe‐layered double hydroxides are grown in situ on three‐dimensional hierarchical Ni supported on Ni mesh. Benefiting from the hierarchically porous structure with highly exposed active sites, effective gas transportation, and fast electron transfer, the resulting NiFe/Ni/Ni electrode exhibits superior activity for overall water splitting with high stability even under a large current density of 500 mA cm−2.