A template-free one-pot hydrothermal route was adopted for the facile synthesis of SnS₂@Cu₂O/reduced graphene oxide (rGO) nanoflowers for supercapacitor electrode materials. The structure and morphology was established using XRD, FTIR, XPS, TEM and FESEM. The electron transfer between the two metal centers in the ternary nanocomposite resulted in an ultra-high specific capacitance of 1800 F g⁻¹ at 0.6 A g⁻¹ in 1 M KOH in a three electrode testing environment. The specific capacitance in a two electrode set-up in 1 M TEABF₄ (in acetonitrile) was measured to be 1290 F g⁻¹ at the fixed current density (CD) of 1 A g⁻¹ and about 90% of the specific capacitance was retained after 1000 consecutive charge–discharge cycles. This ultra-high specific capacitance was complemented by the high energy density of 160.0 W h kg⁻¹ and the superior power delivery rate of 3999.54 W kg⁻¹ at the CD of 10 A g⁻¹ in a three electrode aq. KOH set-up. However, in the two-electrode configuration with organic system (TEABF₄ in acetonitrile), the composite showed an energy density of 458.67 W h kg⁻¹ at the high power delivery rate of 1600 W kg⁻¹ and a current density of 1 A g⁻¹. These remarkable electrochemical properties show the potential of this ternary nanocomposite for the fabrication of high performance supercapacitors.