Abstract: The highly efficient synthesis of nitrogen-doped carbons with different pore structures is reported using shrimp shell as the carbon and nitrogen source, and its CaCO₃ component as the hard template and activator. The CaCO₃ content of shrimp shells can be easily changed by changing the leaching time to remove it. CaCO₃ acts as the activator and template to tailor the pore sizes of the carbons. CO₂ from the decomposition of CaCO₃ also plays an activating role. Their specific surface areas, pore volumes, ratios of micropore volume to total pore volume can be adjusted in the ranges 117.6-1 137 m² g⁻¹, 0.14-0.64 cm³ g⁻¹, and 0-73.4%, respectively. When used as the electrodes of a supercapacitor, the porous carbon obtained with a leaching time of 92 min has a high capacitance of 328 F g⁻¹ at 0.05 A g⁻¹ in a 6 mol L⁻¹ KOH electrolyte and 619.2 F g⁻¹ at 0.05 A g⁻¹ in a 1 mol L⁻¹ H₂SO₄ electrolyte. Its corresponding energy density at a power density of 1 470.9 W kg⁻¹ is 26.0 Wh kg⁻¹. This study provides a low cost method for fabricating porous carbons from biomass with a high added value.