A new facile synthesis of functionalized graphene (fg-p) reinforced bio-based polybenzoxazine nanocomposite (pbf2%-pbf10%) was developed in this work. Cardanol, formaldehyde, and furfuryl amine were used to make a bio-based benzoxazine monomer (bf). bf and benzoxazine polymer (pbf) were characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance spectroscopies, and fg-p was characterized by FT-IR spectroscopy, X-ray diffraction, and scanning electron microscopy. The electrochemical properties of the fg-p sheets and their nanocomposites (pbf2%-pbf10%) were examined using cyclic voltammetry and electrochemical impedance spectroscopy. The results of electrochemical measurements showed that pbf4% has the largest specific capacitance of 78.2 F/g when compared to pbf (36.98 F/g), whichshows that fg-p reinforced pbf nanocomposites have potential application as the high-performance capacitor electrode material.