The biggest problems encountered by the world right now are energy demand and environmental damage because of the exploitation of fossil fuels. Producing and storing energy in an environment-friendly way is increasingly crucial due to the exhaustion of non-renewable resources. Developing a robust energy storing system is essential for efficient energy storage, specifically for renewable energy sources. In this study, tin selenide and manganese telluride (SnSe–MnTe) nanocomposite was synthesized via a sonication method for supercapacitor application. Different physical techniques confirmed the enhanced structural and morphological attributes observed for the SnSe–MnTe nanocomposite. During electrochemical investigations, the SnSe–MnTe nanocomposite exhibited specific capacitance, specific energy (SE) and specific power (SP) of 1502 F/g, 61.05 Wh/kg and 270.5 W/kg at 1.0 A/g, correspondingly. Furthermore, it exhibited outstanding cyclic stability, maintaining its performance across 5000th cycles in an electrolyte (2.0 M KOH). Compared to SnSe (1.25 Ω) and MnTe (0.69 Ω), the charge transfer resistance (Rct) value for SnSe–MnTe (0.3 Ω) was smaller calculated via Nyquist plot. Therefore, transition metal chalcogenide-based nanocomposite has an excellent potential as electrode material for supercapacitor (SCs) and it can also be utilized in different energy storage devices.