<p>Flexible supercapacitors are emerging as promising energy storage devices; however, their performance is generally limited by low specific capacitance, energy density, and power density due to the use of inactive electrode materials during prototype device construction. In this study, activated porous carbon derived from turmeric leaf waste was investigated as a sustainable electrode material for supercapacitors. This approach of biomass waste valorization for electronic device application contributes significantly toward the transition from a linear economy to a circular economy. In this study, highly porous carbon was synthesized from turmeric leaf waste through carbonization and activation with zinc chloride, called turmeric leaf activated porous carbon (TAPC). The formation of amorphous carbon was revealed by XRD and Raman spectroscopy studies. A mesoporous morphology was confirmed by FESEM and BET adsorption–desorption isotherm analysis. The cyclic voltammograms and galvanic charge/discharge curves were perfectly rectangular and triangular, respectively, at different scan rates indicating the rapid charge/discharge capacity of the obtained carbon. A prototype supercapacitor device was fabricated using TAPC as electrodes coated on a carbon cloth substrate whereby Whatmann filter paper immersed in PVA-H₂SO₄ gel electrolyte was used as the separator. The TAPC material exhibited a notable surface area of 720.12 m²/g. The biomass-derived TAPC demonstrated an energy density of 12.39 Wh/kg, power density of 8.92 W/kg, and specific capacitance of 86.64 F/g highlighting its potential for efficient energy storage applications.</p>