<p>The growth in energy crises brought on by fast industrial expansion in the current energy environment makes the development of sophisticated energy storage systems necessary. The remarkable conductivity and storage capacity of transition-metal sulfide-based oxides make them the perfect choice for supercapacitor (SC) cathode materials. Straightforward hydrothermal synthesis and a wet chemical approach were employed to design and create FeS/MgO composite nanoparticles. Compared to as-prepared MgO nanospheres (87 Fg⁻¹) and FeS nanosheets (90 Fg⁻¹), the electrode based on the FeS/MgO composite nanoparticles demonstrated an ultrahigh specific capacity of 350 Fg⁻¹ at 1 Ag⁻¹. Furthermore, because of their synergistic performance, high surface area with many active sites, and hierarchical structure, FeS/MgO composite nanoparticles&#xa0;demonstrated improved rate performance and a good life cycle, maintaining 86% of its capacity after 2000 cycles at 3 Ag⁻¹. Operating within a wide potential window (−&#xa0;0.4–0.8&#xa0;V), FeS/MgO//AC asymmetric supercapacitor device produced a high capacitance of 98.3 Fg⁻¹ at 1 Ag⁻¹, an outstanding energy density of 32.7 Wh kg⁻¹, and a high power density of 4980 W kg⁻¹. This development offers a strong response to the contemporary era’s pressing need for effective and sustainable energy storage. The FeS/MgO electrode’s increased specific capacitance is attributed to the synergistic interaction between Fe²⁺ and Mg²⁺, as well as the presence of nanoparticles with MgO-like morphology, which give the FeS nanoplates a significant surface area and enhance conduction, highlighting the effectiveness of the composite FeS/MgO electrode in ultrachemical capacitors. Enhanced specific capacitance and superior cycling stability are two benefits of FeS/ZnO composite supercapacitors. Energy storage applications can benefit from the synergistic effects of FeS and ZnO, which enhance energy density and power performance.</p>