BACKGROUNDOwing to the significance of metal oxide nanomaterials for energy storage supercapacitors, sustainable, cost‐effective and scalable synthesis of facile nanomaterials is a great challenge in the current era. Here, we have hydrothermally synthesized and functionalized a facile ternary metal oxides (MoO3/NiO/PdO/Pd) nanomaterial using the green phyto‐organic reducing plus stabilizing reagent Euphorbia cognata Boiss foliar extract (FE). The aqueous‐prepared FE was reacted with metal precursors and during this process, free octodrine and cyclobutanol organic functional groups of FE were incorporated as stabilizing agents.RESULTSThe synthesized MoO3/NiO/PdO/Pd demonstrated an optical band gap energy of 1.6 eV. Supercapacitor measurements of prepared MoO3/NiO/PdO/Pd were carried out on nickel (Ni) foam‐modified electrodes via charge–discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV measurements have been recorded at the range of scan rates (2–300 mV s−1) and it was found that the nanocomposite‐modified Ni foam showed a specific capacitance of 257 F g−1 at a scanning rate of 2 mV s−1. Furthermore, from the GCD investigation, it was revealed that 175 F g−1 was achieved at 0.5 A g−1 with a discharge current‐based energy density of 7.2 Wh kg−1. The fabricated electrode showed a 0.4 Ω resistance value from the impedance Nyquist plot.CONCLUSIONThe study concluded that the MoO3/NiO/PdO/Pd nanocomposite with the smaller synergistic band gap and catalytic advantage of phytostabilizing agents revealed exceptional capacitive properties, validating its potential as a supercapacitor electrode. © 2023 Society of Chemical Industry (SCI).