A pine‐shaped Pt nanostructured electrode with under‐water superaerophobicity for ultrahigh and steady hydrogen evolution reaction (HER) performance is successfully fabricated by a facile and easily scalable electrodeposition technique. Due to the lower bubble adhesive force (11.5 ± 1.2 μN), the higher bubble contact angle (161.3° ± 3.4°) in aqueous solution, and the smaller size of bubbles release for pine‐shaped Pt nanostructured electrode, the incomparable under‐water superaerophobicity for final repellence of bubbles from submerged surface with ease, is successfully achieved, compared to that for nanosphere electrode and for Pt flat electrode. With the merits of superior under‐water superaerophobicity and excellent nanoarray morphology, pine‐shaped Pt nanostructured electrode with the ultrahigh electrocatalytic HER performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase at overpotential range (3.85 mA mV−1, 2.55 and 13.75 times higher than that for nanosphere electrode and for Pt flat electrode, respectively), is obtained, much superior to Pt nanosphere and flat electrodes. The successful introduction of under‐water superaerophobicity to in‐time repel as‐formed H2 bubbles may open up a new pathway for designing more efficient electrocatalysts with potentially practical utilization in the near future. A Pt nanoarray electrode with under‐water superaerophobicity is fabricated by a facile and easily scalable electrodeposition technique. This electrode with a lower bubble adhesive force, a higher bubble contact angle in aqueous solution, and lower size of bubbles release, exhibits an ultrahigh electrocatalytic hydrogen evolution reaction performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase.