Homogeneous copper incorporated nickel sulfide (NS) nanosheets were realized via an in situ ion exchange method and one-pot hydrothermal process. Nickel foam (NF) and copper foam (CF) were used as metal sources for the co-formation of Cu_1.8S–Ni₃S₂ in the presence of thiourea. As a result of the Cu incorporation, the NF-supported Ni₃S₂ nanosheets exhibited improved electronic conductivity with higher electrochemical surface area (ECSA). When evaluated as electrode materials for supercapacitors, the as-obtained active materials demonstrated high specific capacitance (1686 F g⁻¹ at 1 A g⁻¹) with excellent cycling performance (95.39% capacitive retention after 10 000 cycles), which may be attributed to the unique structural features as well as the synergistic effect of localized copper species with Ni₃S₂ nanosheets.