A new nanocomposite based on CuCo₂S₄ nanosheets and polyaniline conducting polymer is synthesized and introduced as an electrode material for energy storage supercapacitors. First, CuCo₂S₄ nanosheets are prepared on carbon cloth through hydrothermal route and a wide potential window of 1.2 V is obtained for this material in Na₂SO₄ electrolyte. Then, a nanocomposite with an optimized amount of polyaniline is synthesized through chemical polymerization of aniline monomer on the surface of CuCo₂S₄ nanosheets and its electrochemical behavior is studied. Regarding the synergistic effect between polyaniline and CuCo₂S₄, the resultant CuCo₂S₄/polyaniline electrode exhibits a wider potential range and an improved specific capacitance of 920 F g⁻¹ at a current density of 1 A g⁻¹, significantly higher compared to that of bare CuCo₂S₄ nanosheets (780 F g⁻¹). Symmetric supercapacitor assembled by newly prepared CuCo₂S₄/polyaniline as both anode and cathode, demonstrated extended operating potential window (1.8 V) and delivered high energy density of 32.5 Wh kg⁻¹ and power density of 900 W kg⁻¹. These results confirm that the as-prepared nanocomposite exhibits improved electrochemical performance and is a promising candidate to be used in energy storage devices.