In this study, a rapid, cost-effective, and environment-friendly method based on flash Joule heating (FJH) has been implemented to fabricate tungsten carbide catalysts with optimized phases, as efficient alternatives to Pt, for high-performance acidic hydrogen production at industrial-level current densities. A series of tungsten carbide electrodes were synthesized with different FJH durations (3, 10, 30, and 60 seconds) to tailor the phase composition of WC and W2C. The results revealed that the sample synthesized for 30 seconds (denoted as TC-3) exhibited the optimal performance at a high current density of 4 A/cm 2 , attributed to the optimized ratio of WC to W2C phases and resulting synergistic effects. Remarkably, the TC-3 sample demonstrated exceptional stability, maintaining its performance for over 6 days of continuous operation at 4 A/cm 2 , ascribed to the inherent corrosion-resistant properties of tungsten carbide and strong tungsten-carbon bonding. This work paves the way for the scalable production of cost-effective and robust tungsten carbide catalysts outperforming Pt, particularly for high-current-density industrial hydrogen production applications where high throughput and long-term stability are crucial.