The ever-growing demand for energy storage devices necessitates the development of novel energy storage materials with high performance. In this work, copper molybdenum sulfide (Cu2MoS4) nanostructures were prepared via a one-pot hydrothermal method and examined as an advanced electrode material for supercapacitor. Physico-chemical characterizations such as X-ray diffraction, laser Raman, field emission scanning electron microscope with elemental mapping, and X-ray photoelectron spectroscopy analyses revealed the formation of I-phase Cu2MoS4. Electrochemical analysis using cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) showed the pseudocapacitive nature of charge-storage via ion intercalation/de-intercalation occurring in the Cu2MoS4 electrode. The Cu2MoS4 electrode delivered a specific capacitance of 127 F g−1 obtained from the CD measured using a constant current density of 1.5 mA cm−2. Further, Cu2MoS4 symmetric supercapacitor (SSC) device delivered a specific capacitance of 28.25 F g−1 at a current density of 0.25 mA cm−2 with excellent rate capability. The device acquired high energy and power density of 3.92 Wh kg−1 and 1250 W kg−1, respectively. The Nyquist and Bode analysis further confirmed the pseudocapacitive nature of Cu2MoS4 electrodes. The experimental results indicate the potential application of Cu2MoS4 nanostructures as a novel electrode material for energy storage devices.