Biomass-derived porous carbon materials have drawn considerable attention due to their natural abundance and low cost. In this work, nitrogen enriched porous carbons (NRPCs) with large surface areas were designed and prepared from cottonseed hull via simultaneous carbonization and activation with a facile one-pot approach. The NRPCs were tunable in terms of pore structure, nitrogen content and morphology by adjusting the ratio of the carbon precursor (cottonseed hull), nitrogen source (urea), and activation agent (KOH). The as-synthesized NRPCs exhibited three-dimensional oriented and interlinked porous structure, high specific surface area (1160-2573 m(2) g(-1)) and a high level of nitrogen-doping (6.02-10.7%). In a three electrode system, NRPCs prepared at 800 degrees C with the ratio (cottonseed hull:KOH:urea) of 1:1:2 (NRPC-112) showed a high specific capacitance of 340 F g(-1) at a current density of 0.5 A g(-1) and good rate capability (approximate to 80% retention at a current density of 10 A g(-1)) with 6 M KOH as electrolyte. In a two electrode cell, NRPC-112 demonstrated a high specific capacitance of 304 F g(-1) at 0.5 A g(-1) and an excellent rate capacity (approximate to 71% retention at current density of 10 A g(-1)) as well as excellent cycling stability (approximate to 91% retention at 5 A g(-1)) after 5000 cycles. Furthermore, the NRPCs exhibited an extraordinary adsorption capacity up to 205 mg g(-1) for emerging pollutant triclosan. The work provided a sustainable approach to prepare functional carbon materials from biomass-based resource for environment remediation and electrochemical applications.