Herein, we report a novel and facile strategy for the construction of nitrogen-doped hierarchically porous carbons (NHPCs) derived from citrate salts and ammonium chloride (NH₄Cl) by a phase-transition-assisted method. During pyrolysis, NH₄Cl decomposed into gas and citrate salts transformed into liquid at nearly the same temperature interval, such a phase transition of precursor leads to the formation of NHPCs. The decomposed NH₃ gas contributes by enriching the N-dopant concentration to fabricate nitrogen-doped carbons, and HCl gas promotes the dispersion of the cation of citrate salts to facilitate the formation of NHPCs. Altering the cation of citrate salts, we can tune the pore structure of NHPCs from macroporous rich to microporous rich pore structure. Benefiting from the large specific surface area and hierarchical porous structure, the NHPCs exhibited excellent catalytic activity for ORR, and also served as a highly stable electrode material for supercapacitors.