The demand for economic and efficient electrode for energy storage devices has been increased with the rapid advancements in the sustainable synthesis of active material. Herein, bioactive compounds as fuel for the synthesis of electrode material (Co3O4 NPs), were investigated. Functionalization of Co3O4 NPs via organic extract of Euphorbia cognata Boiss have not only revealed the rapid and efficient growth of active materials but also ensured an effective interaction between the fabricated electrode and electrolyte solution for charge storage reactions. The synthesized Co3O4 NPs were scrutinized for its optical, structural, compositional and chemical properties and then investigated by galvanostatic charge discharge, cyclicvoltammetry for determination of its energy storage potential. The fabricated electrode was tested at range of scan rates and current densities to evaluate its charge storage potential at different scan rates and current densities. The phytofunctionalized Co3O4 NPs offered a large accessible active sites for charge storage with capacitance of 103 Fg-1, a maximum energy density of 1.9 Whkg−1, and higher power density of 4.7 KWkg−1. Thus, we have demonstrated the sustainable fabrication of electrode for energy storage applications. •E. cognata Co3O4 nano electrode of supercapacitor.•The specfic capacitance of 103 Fg−1.•Biomimetic Co3O4 for energy storage.