This paper reports an ultra-facile and energy-efficient microwave irradiation method for fabrication of phosphorus doped mesoporous carbon under ambient atmosphere. The fabricated phosphorus doped mesoporous carbons exhibit high specific surface area (up to 2055 m(2) g(-1)), large pore volume (up to 2.73 cm(3) g(-1)) and good conductivity, which specific capacitance reaches up to 210 F g(-1), over 201 F g(-1) of capacitance is retained even under a high current density of 20 A g(-1), and the capacitance retention arrives 97.39% after 10,000 times charge/discharge cycles. Comparative study reveals that similar morphology is obtained by microwave irradiation and traditional pyrolytic carbonization, but more developed porosity and higher graphitization degree are achieved under microwave irradiation. The carbonization process completes in 1-3 min under microwave irradiation, which generally spends more than 2 h at a high temperature of over 600 degrees C by traditional pyrolytic method. No dramatic increase for surface oxygen content is found even it was fabricated under ambient atmosphere. The samples fabricated under microwave irradiation are potentially cost-efficient and high-performance electrode material for commercial supercapacitors.