In this research work, we have successfully synthesized a ternary nanocomposite (PEDOT/rGO/HfS2) by combining poly[3,4-ethylenedioxythiophene (PEDOT)], reduced graphene oxide (rGO), and Hafnium disulfide (HfS2) using a simple in situ polymerization and hydrothermal technique for energy storage applications. The XRD, Raman, TGA, XPS, TEM, and FESEM techniques were utilized to examine the thermal, structural, and chemical composition and morphology of the as-prepared samples. The TGA result confirms that the PEDOT/ rGO/HfS2 ternary nanocomposite electrode has the highest weight retention value in comparison to pure PEDOT, PEDOT/rGO, and PEDOT/HfS2 synthesized electrodes. It indicates that the PEDOT/rGO/HfS2 ternary nano- composite achieved the highest thermal stability. The electrochemical characteristics of the PEDOT/rGO/HfS2 nanocomposite are assessed using CV and GCD experiments. The PEDOT/rGO/HfS2 ternary nanocomposite electrode displayed enhanced specific capacitance, reduced charge transfer resistance, and improved cycle stability in comparison to the individual PEDOT, PEDOT/rGO, and PEDOT/HfS2 electrodes, owing to the strong interactions between PEDOT, rGO, and HfS2. Furthermore, the presence of rGO had a remarkable impact on PEDOT's durability and electrical storage capacity. This highlights the beneficial effects of rGO, resulting in the attainment of the highest specific capacitance (1015 Fg-1 at 5 Ag-1), exceptional ability to maintain performance at different charging rates, and impressive retention of capacitance (98.1 % over 10,000 cycles at 5 Ag-1). The PEDOT/rGO/HfS2 hybrid electrode exhibits a remarkable specific energy of 171 Wh kg-1 at a specific power of 2457 W kg-1. After 10,000 cycles, the capacitance only decreases by 1.9 % of its initial amount. The PEDOT/ rGO/HfS2 ternary nanocomposite demonstrates excellent long-term cyclic stability, as seen by its 98.1 % capacitance retention after 10,000 consecutive cycles. This suggests that it is a highly efficient, cost-effective, and promising electrode material for further investigations in supercapacitors. Hence, this technique will facilitate the development of a next-generation of sophisticated electrode materials for the storage of energy.