Triazine graphitic nanoplatelets (TGNP) were synthesized as an anchor to improve the activity and stability of Pt nanoparticles for the hydrogen evolution reaction (HER). Pt@TGNP, Pt supported on TGNP, showed high performance (i.e., high activity and stability) for HER under acidic conditions. Although Pt@TGNP contained very low Pt content (8.7 wt%), it exhibited much better activity (overpotential: 32 mV, Tafel slope: 28.4 mV dec(-1)) and stability (overpotential increase: 1.6 mV) for HER, compared with Pt/C (overpotential: 35 mV, Tafel slope: 29.2 mV dec(-1), and overpotential increase: 6.2 mV). The results convincingly demonstrate that the triazine units of TGNP offer active sites that increase catalytic activity, as well as anchoring sites to prevent the aggregation of Pt nanoparticles. Results confirmed that Pt@TGNP with its efficient catalytic activity and stability is a promising alternative to existing Pt-based catalysts, and TGNP with triazine is highly likely to be utilized as a catalyst support in various applications.