In this work, a supercapacitor (SC) designed for flexible and wearable textile systems operating in environments similar to biological fluids is presented. Supercapacitor electrode (SE) uses electrodes composed of derivatized coumarin poly(3,4-ethylenedioxythiophene)/7-Hydroxy-4-phenyl-2H-chromen-2-one (SE1), poly(3,4-ethylenedioxythiophene)/7-Hydroxy-8-(((1-hydroxy-3-phenylpropan-2-yl)imino)methyl)-4-phenyl-2H-chromen-2-one (SE3) and poly(3,4-ethylenedioxythiophene/Ethyl-2-(((7-hydroxy-2-oxo-4-phenyl-2H-chromen-8-yl)methylene) amino)-3-(4-hydroxyphenyl) propanoate (SE4) in 3.0 M NaCl as the electrolyte. The SE4 shows ultra-high specific capacitance of 2852.6 F g−1 (14.3 F cm−2) at a current density of 1.0 A g−1 (5.0 mA cm−2). The energy and power densities of the symmetric supercapacitor consisting of SE4 were 46.7 Wh/kg and 800.0 W kg−1, respectively for 1.0 V and its specific capacitance is 672.6 F g−1. SC exhibits a capacitance retention of 113.6% by charging/discharging stability (15,000 cycles). Cyclic voltammograms generated by twisting and bending the flexible supercapacitor at various angles (0–180°) are successfully carried out. SC was made that shows the operation of a red LED light when charged with a battery. The device, created through the use of aqueous electrolyte systems such as Na+, Cl− ions, has demonstrated significant performance as a safe and sustainable way to meet the energy and power density requirements in wearable electronic systems.