Water electrolysis is a sustainable means by which to produce hydrogen, an alternative energy source for fossil fuels. The efficiency of this process relies on the electrocatalysts used in the hydrogen evolution reaction (HER). Platinum (Pt) is a widely used catalyst that has excellent electrocatalytic activity, but its considerable cost and limited durability hinder its widespread application. In this study, a novel electrocatalyst, Pt&A-N-GN, is prepared simply by depositing Pt onto activated nitrogen-doped graphitic nanoplatelets (A-N-GN) with a high surface area and appropriate porosity. Through nitrogen (N)-doping and activation processes, the physicochemical properties of the graphitic nanoplatelet (GNP) as a support are significantly enhanced. As a result, despite the very low Pt content (5.27 wt%), Pt&A-N-GN shows outstanding HER activity and stability under acidic conditions compared to the commercial Pt/C, suggesting that the enhanced interaction between the structurally modified carbon support and metal nanoparticles can provide an effective and economical alternative to Pt-based catalysts.