Porous carbon materials have received considerable attention recently, particularly in the energy field. To meet the increasing demands for electrochemical energy conversion and storage-related applications, the development of novel porous carbon materials that show high electrochemical performances is highly desired. Here, a facile method for the preparation of nitrogen-doped hierarchically porous carbon materials is proposed. Cost-effective chitosan is selected as the nitrogen-containing carbon source, and the carbonation is realized in a ZnCl₂ molten salt at a temperature range of 400–700 °C. Hierarchically porous carbon with a specific surface area of 1582 m² g⁻¹ and a high nitrogen content of 9.0 wt.% is obtained at a carbonation temperature of 600 °C with a high carbon yield of 42 wt.% based on the weight of chitosan. Importantly, using this as-synthesized carbon material as the electrode in supercapacitors, high specific capacitances of 252 and 145 F g⁻¹ at current densities of 0.5 and 50 A g⁻¹, respectively, and stable cycling performance without decay after 10,000 cycles at 8 A g⁻¹ are realized. The facile synthesis, easy recovery of ZnCl₂ and high carbon yield make this new method highly promising for the preparation of porous carbon materials for use in supercapacitors and other fields.