In this study, the preparation of activated carbons (ACs) via acidic dehydration of durian husk (DH) for supercapacitor application was investigated. The DH was dehydrated using sulfuric acid and subsequently activated by using sodium hydroxide as chemical reagent at 720 °C to obtain activated carbon (hereinafter referred to as DA). Surpassing the commercial ACs and the ACs derived from the conventional carbonization and activation (hereinafter referred to as CA), the DA exhibited superior properties in high surface area (2578 m2/g) and total pore volume (1.27 cm3/g). Moreover, besides carbon and oxygen, the DA contained sulfur and nitrogen in the carbon network. The DA can act as a suitable material for supercapacitor electrode with the specific gravimetric and volumetric capacitances of 145 F/g and 70 F/cm3 in an organic electrolyte. The device also showed a promising performance with an energy density of 32 Wh/kg and a power density of 316 W/kg. These results demonstrate that the preparation of ACs via acidic dehydration of DH offers the advantages in terms of simplicity, low cost, and short-time processing to achieve heteroatom self-doped ACs with a high surface area for high-performance supercapacitors.