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α-Ga2O3 microrods was deposited on carbon cloth (CC) using a hydrothermal process followed by a high-temperature annealing in air. The microstructure of the obtained Ga2O3/CC composite electrodes were characterized with scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Their electrochemical performances were tested with electrochemical impedance spectroscopy (EIS), Mott-Schottky (MS), cyclic voltammetry (CV) and galvanostatic charge/discharge techniques (GCD). By comparing the electron densities and mobilities of the Ga2O3/CC electrodes prepared with different hydrothermal durations, the doping mechanisms of point defects in α-Ga2O3 were revealed. The point defects in α-Ga2O3 including Ga-oxygen vacancies (Ga-VO), gallium vacancies (VGa), and VGa-VO complexes were all identified as the scattering centers. By extending the hydrothermal duration to more than 6 h, the electronic conductivity of the Ga2O3/CC electrode was enhanced by reducing the number of point defects in α-Ga2O3. The Ga2O3/CC-6h aqueous symmetrical supercapacitor (SC) showed a remarkable increase in the electrochemical performance by exhibiting a specific areal capacitance of 1394 mF cm−2 at 0.5 mA cm−2, with 67% of the capacitance retained when the current density was increased to 20 mA cm−2, and 76.5% of capacitance retention after 20,000 cycles under a current density of 10 mA cm−2. The point defect mechanism identified in the article would pave the way to develop novel energy storage devices based on α-Ga2O3 in the future. [ABSTRACT FROM AUTHOR]