The present study demonstrates a facile, one-step pyrolysis method to synthesize porous carbon nanoparticles using widely distributedMimosa pudica(Touch-me-not) biomass leaves at different temperatures. Multiple characterization techniques (N(2)adsorption-desorption experiments, FESEM, XRD, Raman spectroscopy, XPS) demonstrate the morphological nature and excellent surface properties, with the surface area up to 440.7 m(2)g(-1). The electrochemical studies of as-synthesized porous carbon nanoparticles, as electrodes, were carried out in both three and two electrode setups. The maximum specific capacitance obtained was 356.1 F g(-1)at 0.1 A g(-1)in 4.0 M KOH electrolyte. The symmetric supercapacitor showed a specific capacitance of 126.8 F g(-1)at 0.1 A g(-1)and a high energy density of 34.5 Wh kg(-1). The device also showed impeccable stability for 10,000 galvanostatic charge-discharge cycles with 99.2% Coulombic efficiency and capacitance retention of 81.39%. The stability of the device was investigated by floating method (aging), which showed 86.8% capacitance retention, suggesting a huge capacity of biomass-derived carbon materials for efficient and stable high-performance electrodes in electrochemical energy storage applications using an environmental-friendly approach. This study illustrates a sustainable approach to produce porous carbon nanoparticles for effective energy storage devices. Graphic abstract