Introducing and using novel conductive organic–inorganic material systems for the supercapacitor industry is rapidly emerging. In this work, the well-defined MCo2O4 nanospheres (M: Mn, Ni) are successfully grown on the graphitic carbon nitride/polypyrrole (g-C3N4@PPy) nanoparticles by hydrothermal/polymerization process. XPS, FT-IR, XRD, BET, and SEM techniques were employed to investigate the physical and chemical properties as well as the surface characteristics of MCo2O4 nanospheres. The electrochemical behavior of the developed electrode was investigated by electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Moreover, owing to the advantageous proportion of aspect ratio and relatively low electrode and electrolyte resistance, the highest specific capacitance value for g-C3N4@PPy@MnCo2O4 and g-C3N4@PPy@NiCo2O4 supercapacitors was obtained as 350.00 and 258.26 F g−1, with a current density of 0.5 A g−1, respectively. Also, capacitance retention of supercapacitors after 5000 GCD cycles was achieved by 92.71 %, and 94.55 % respectively. These results demonstrate that the decorated nanospheres on g-C3N4@PPy exhibit excellent capacitive properties and stability, indicating their potential for use in the field of energy storage.