In this study, TiO2 nanoparticles at different weight ratios were added to composite coconutshell carbon and conductive carbon black electrode material to investigate their effects on the properties of a supercapacitor. Then, the composite carbon electrodes were further treated by rapid thermal annealing (RTA) and measured by field emission scanning electron microscopy (FE-SEM), electronic data system (EDS) analysis, cyclic voltammetry (CV), and charge–discharge and photoluminescence (PL) tests to investigate the diverse effects on the electrodes with conductive carbon black doped with TiO2 nanoparticles and on the electrodes treated with and without RTA. According to the results of CV, the capacitance of electrodes without TiO2 nanoparticles was determined to be 73.104 F/g by scanning at a rate of 25 mV/s, and could be increased to 96.54 F/g with TiO2-doped carbon electrodes. In addition, the capacitance of carbon electrodes with TiO2 could be increased to 171.28 F/g after heat treatment by RTA.