The practical application of electrochemical water splitting has been plagued by the sluggish kinetics of bubble generation and the slow escape of bubbles which block reaction surfaces at high current densities. Here, 3D-printed Ni (3DP Ni) electrodes with a rationally designed periodic structure and surface chemistry are reported, where the macroscopic ordered pores allow fast bubble evolution and emission, while the microporosity ensures a high electrochemically active surface area (ECSA). When they are further loaded with MoNi 4 and NiFe layered double hydroxide active materials, the 3D electrodes deliver 500 mA cm -2 at an overpotential of 104 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER), respectively. An all-3D-printed alkaline electrolyzer (including electrodes, membrane, and cell) delivers 500 mA cm -2 at a remarkable voltage of 1.63 V with no noticeable performance decay after 1000 h. Such a tailored bubble trajectory demonstrates feasible solutions for future large-scale clean energy production.