Nitrogen-doped carbon aerogels (NCAs) have received great attention for a wide range of applications, from thermal electronics to waste water purification, heavy metal or gas adsorption, energy storage, and catalyst supports. Herein NCAs are developed via the synthesis of a Schiff-base porous organic polymer aerogel followed by pyrolysis. By controlling the pyrolysis temperature, the polymer aerogel can be simply converted into porous NCAs with a low bulk density (5 mg cm(-3)), high surface area (2356 m(2) g(-1)), and high bulk porosity (70%). The NCAs containing 1.8-5.3 wt% N atoms exhibit remarkable CO2 uptake capacities (6.1 mmol g(-1) at 273 K and 1 bar, 33.1 mmol g(-1) at 323 K and 30 bar) and high ideal adsorption solution theory selectivity (47.8) at ambient pressure. Supercapacitors fabricated with NCAs display high specific capacitance (300 F g(-1) at 0.5 A g(-1)), fast rate (charge to 221 F g(-1) within only 17 s), and high stability (retained >98% capacity after 5000 cycles). Asymmetric supercapacitors assembled with NCAs also show high energy density and power density with maximal values of 30.5 Wh kg(-1) and 7088 W kg(-1), respectively. The outstanding CO2 uptake and energy storage abilities are attributed to the ultra-high surface area, N-doping, conductivity, and rigidity of NCA frameworks.