The development and advantages of wearable flexible electronics have become attractive issues with excellent electrochemical performances in energy storage devices. In this study, we highlighted a low cost and green fabrication of bio-supercapacitor using poly(vinyl alcohol) (PVA):Nano-eggshell microcomposites. As it is known, interest in the production of green supercapacitors is increasing rapidly. A uniform PVA:Nano-eggshell microcomposite morphology was obtained in the polymer blend-based nanostructure using kappa-carrageenan as the matrix. PVA:Nano-eggshell microcomposites were prepared and coated on a Ni foam. The performance of PVA:Nano-eggshell microcomposites-Ni foam-based supercapacitor was investigated. Kappa-carrageenan was used to increase the specific capacity due to the large number of free charges. The proposed supercapacitor showed a high specific capacitance of 255 F/g in [0, 1] V range at 100 mV/s scan rate. These results demonstrated that the proposed electrode of PVA:Nano-eggshell microcomposites is to be a promising high performance and flexible supercapacitor in energy storage applications.