Porous carbon with a high surface area has attracted wide attention in energy storage systems due to its fast charge−discharge rate and exceptional rate capability. However, it is still a challenge to design electrochemical capacitors with both high energy density and power density by using low-cost electrode materials. Herein, we report a novel strategy of simultaneous dehalogenation and nitrogen doping to prepare nitrogen-doped porous carbon materials. Ethylenediamine is used as a dehalogenation agent, a structural modifier, and a nitrogen source. The optimal sample (CPVDC-3) has a high specific surface area of ∼3120 m2 g−1 with a large pore volume. An excellent electrochemical as well as energy storage behavior is shown in supercapacitors as tested in three-electrode and two-electrode system. The as-synthesized CPVDC-3 sample obtains a high specific capacitance of 402 F·g−1 at a current density of 0.5 A·g−1 in KOH. Furthermore, a specific energy of 11.1 W·h·kg−1 is obtained at the power density of 124.9 W·kg−1. The obtained nitrogen-doped porous carbon material exhibits enhanced electrochemical performance due to its high surface area and hierarchically porous structure. This work highlights a simple and feasible method to design and prepare nitrogen-doped carbon for supercapacitors, which is expected to realize the reuse of polyvinylidene chloride and alleviate the environmental pollution caused by this compound.