Abstract Highly porous materials with a 3D framework have been produced by a sustainable salt template‐assisted chemical activation approach based on the use of KCl particles as template, K 2 CO 3 particles as both template and activating agent, and biomass‐derivatives as carbon precursor (i. e., glucose and soybean meal). The self‐assembly of all the constituents into a 3D structure is achieved by a freeze‐drying process. After carbonization and a simple washing step with water, a 3D hierarchical porous carbon is obtained. The sustainability of the process is ensured by using chemicals of low or null toxicity and renewable carbon precursors. The materials produced are characterized by a 3D framework composed of thin walls rich in micropores, with BET surface areas in excess of 2000 m 2 g −1 and pore volumes of up to 1.4 cm 3 g −1 . These materials show an improved rate capability in supercapacitors based on aqueous (H 2 SO 4 and Li 2 SO 4 ) and ionic liquid electrolytes (EMImTFSI/AN) with carbon electrode loadings well within the range of commercial values.