Efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) in natural seawater environments are essential for sustainable hydrogen production. We synthesized zeolitic imidazolate framework-8 (ZIF-8) through pulsed laser ablation in liquid, followed by pyrolysis, producing N-doped porous carbon (NC). NC matrix served as a self-template, enabling Pt nanocluster decoration (NC-Pt) via pulsed laser irradiation in liquid. NC-Pt exhibits a large surface area, porous structure, high conductivity, N-rich carbon, abundant active sites, low Pt content, and a strong NC-Pt interaction. These properties enhance efficient mass transport during the HER. Remarkably, the optimized NC-Pt-4 catalyst achieved low HER overpotentials of 52, 57, and 53 mV to attain 10 mA cm−2 in alkaline, natural seawater, and simulated seawater, surpassing commercial Pt/C catalysts. In a two-electrode system with NC-Pt-4(−)ǀǀIrO2(+) as cathode and anode, it demonstrated excellent direct seawater electrolysis performance, with a low cell voltage of 1.63 mV to attain 10 mA cm−2 and remarkable stability. This study presents a rapid and efficient method for fabricating cost-effective and highly effective electrocatalysts for hydrogen production in alkaline and natural seawater environments.