Water electrolysis is central to sustainable hydrogen production, yet bubbles adhering to electrodes block active sites and impose mechanical stress on catalysts, diminishing both efficiency and durability. Although polymeric interfacial coatings have been explored to assist bubble removal, mechanistic understanding and durability driven design principles remain underexplored. Here, we establish chemically robust hydrogels for alkaline operation, deploying an ultrathin venting skin that simultaneously shields the catalysts. We combined molecular dynamics simulation (MD) with scalable coating control to substantiate a hydration-layer–mediated slip effect across the hydrogel design space governing bubble dynamics. Validation across half- and full-cell configurations under harsh alkaline conditions confirms that the hydrogel coating accelerates bubble release while maintaining interfacial integrity, providing design principles for polymeric coatings in gas-evolving electrochemistry.