Because of the sustainability, cost-effectiveness, and simplicity of fabrication of meso/microporous carbon synthesized from various precursors, including plants, the production, and application of biomass-derived carbon in energy storage have piqued the interest of researchers. A chemical activation technique involving KOH and carbonization at 600 °C in inert gas was used to successfully synthesize activated carbons (AC) derived from willow catkin (WC). The AC sample was characterized using X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and Transmission electron microscopy (TEM). In 3M KOH aqueous electrolyte, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were employed to elucidate the electrochemical performance of the AC electrode. The AC electrode has a specific capacitance of 105 F. g-1 and exhibited good cycling stability with a capacitance retention of 89.23% after 1000 cycles. The prepared sample is used as an electrode material for a supercapacitor.