The oxygen reduction reaction (ORR) at the cathode is a critical process in fuel cells. This reaction occurs at the gas-liquid-solid triple-phase boundary where gaseous oxygen, liquid electrolyte and solid catalysts interact. As a heterogeneous catalytic reaction, the ORR catalytic efficiency is significantly influenced by mass transport of reactants/products and intrinsic activity of catalysts. Optimizing these factors is essential for improving ORR performance and enhancing energy conversion efficiency. Carbon-based materials are ideal ORR catalysts due to their high electrical conductivity, mechanical stability and tunable structures. However, conventional carbon-based catalysts often suffer from a low density of active site and thick catalyst layers, which may lead to poor performance in practical applications. In this study, the designed nano-sized melamine-formaldehyde resin (NMRS) was employed as both a hard template and nitrogen source, while glucose served as carbon source. A nitrogen rich precursor was synthesized via hydrothermal method, followed by pyrolysis and ammonia activation to obtain nitrogen-doped mesoporous carbon. During pyrolysis, the small diameter NMRS decomposed completely, releasing nitrogen-containing gases and generating mesopores, thereby facilitating uniform nitrogen doping within the carbon matrix. Further ammonia activation enhanced the micro-porosity of the material. The prepared catalyst possessed a high specific surface area of 742 m2 g−1 and a nitrogen content of 5.57%. Its hierarchical porous architecture significantly enhances mass transport during the ORR process. The catalyst demonstrated excellent electrocatalytic performance in alkaline electrolyte, with a half-wave potential of 0.845 V, a limiting current density of 5.2 mA cm−2, and a Tafel slope of 79 mV dec−1, comparable to commercial Pt/C and superior to most metal-free carbon catalysts. Furthermore, the catalysts proceeded ORR via an efficient four-electron pathway. This work presents an effective strategy for designing high performance nitrogen doped ORR catalysts for energy conversion applications.