Water　splitting　serves　as　a　cornerstone　technology　in　modern　energy　conversion　and　storage　systems.　However,　its　industrial-scale　implementation　remains　constrained　by　dynamic　interfacial　destabilization　caused　by　intense　bubble　evolution　under　high　current　densities.　Herein,　a　laser-assisted　fabrication　strategy　is　dveloped　utilizing　selective　laser　melting　to　construct　3D　metallic　electrodes　with　macro-micro　synergetic　architectures,　enabled　by　precise　laser　energy　density　control　for　simultaneous　optimization　of　water　splitting　and　bubble　transport　dynamics.　The　engineered　3D　microporous　structure　electrode　integrates　macro-scale　3D　channels　for　accelerated　mass　transfer　with　micro-scale　in　situ-grown　spherical　substrates　functionalized　by　nickel-iron　layered　double　hydroxide　(NiFe　LDH)　catalysts,　establishing　a　hierarchical　architecture　denoted　as　NiFe　LDH/3D　printing　(NF/3DP).　Interestingly,　Laser-tuned　surface　roughness　confers　superhydrophilicity,　gas　repellency,　and　low　bubble　adhesion.　Collaborative　3D　channel　design　significantly　reduces　concentration　polarization　and　achieves　efficient　mass　transfer　at　the　solid-liquid-gas　three-phase　interface.　Notably,　the　NF/3DP　electrode　only　requires　a　330　mV　overpotential　to　drive　the　oxygen　evolution　reaction　(OER)　at　an　industrial　current　density　of　1000　mA　cm−2,　and　maintains　initial　activity　even　after　continuous　operation　for　1000　h　at　500　mA　cm−2.　This　strategy　supports　flexible　assembly　like　Lego　through　modular　interface　design,　providing　a　standardized　manufacturing　and　scalable　technical　solution　for　customized　hydrogen　production　systems.　©　2025　Wiley-VCH　GmbH.