AbstractNickel‐based electrocatalysts are deemed as promising low‐cost, earth‐abundant materials in the development of the next‐generation alkaline and anion exchange membrane water electrolyzers. Herein, a plasma‐processing technique is presented for fabricating self‐supported nanostructures from planar NiFe substrates and its performance for water splitting reactions. Irradiating the samples with helium plasma results in the formation of nano‐tendrils, which are affixed to the metallic substrate. This unique design not only enhances charge and mass transport, but also increases the electrochemical surface area by 3 to4 times, as compared to the unmodified/planar surfaces. For the benchmark 10 mAcm−2geo current density, the nanostructured electrodes demonstrate overpotentials of 330 and 354 mV for oxygen evolution reaction and hydrogen evolution reaction respectively in 1 M‐ KOH. Moving forward, application of this technique can be extended for fabricating self‐supported 3D substrates (e.g., foams, felts, perforated sheets), all of which find practical applications in energy conversion and storage devices.