Energy storage materials, particularly chalcogenides, are fascinating electrode materials for supercapacitors (SCs) because of their high capacitance, remarkable electrical conductivity, and multiple oxidation states contributed by numerous metal cations. Herein, a novel nanocomposite based on zinc sulfide and copper diselenide, denoted as (ZnS–CuSe₂), was prepared via a sonochemical-assisted method. The structural analysis revealed the cubic structure for pure ZnS, orthorhombic for CuSe_2, and co-existing cubic and orthorhombic phases for ZnS–CuSe₂ nanocomposites with high purity and crystallinity. The ZnS–CuSe₂ nanocomposite offered exceptional electrochemical performance with redox peaks from the CV analysis, and coupled with plateaus in the charge/discharge profile, confirming the faradaic energy storage properties with functional reversibility. Similarly, a high conductive feature of the ZnS–CuSe₂ composite was revealed by impedance study, with a minor charge transfer resistance than their bulk materials. A hybrid asymmetric supercapacitor (HASCs) composed of ZnS–CuSe₂//AC was constructed, which manifested an enlarged voltage window up to 1.7 V with capacitance of 95 F g⁻¹ and a maximum specific energy of 38 Wh kg⁻¹. Also, high power delivery was attained at 3927 Wkg^-1 when specific energy goes down to 12 Wh kg⁻ at 5 A g⁻¹. Interestingly, only 81.8% retention was left beneath when cycled to 8000 cycles, specifying decent stability of the ZnS–CuSe₂//AC HASCs.