The question of how to recycle anaerobic digester residue is a critical issue for the anaerobic digestion process of lignocellulosic biomass. In the current study, anaerobic digester residue from a biogas plant for the treatment of cattle manure was utilized to prepare the activated carbon for supercapacitors. The effect of activation temperature on the specific surface area, pore size distribution, and electrochemical performance of activated carbon was investigated. Results show that activated carbon derived from anaerobic digester residue is feasible for supercapacitors. With an increase in activation temperature, the specific surface area of activated carbon first increases and then gradually decreases. Activated carbon obtained at 700 degrees C shows both high specific capacitance and excellent electrochemical cycle stability. The good capacitive performance confirms that anaerobic digested manure residue can act as an excellent carbonaceous material for high-performance supercapacitors.