A novel electrode material for supercapacitor has been developed based on biochemically reduced graphene oxide/zerovalent iron (rGO/Fe$^0$) and polyaniline (PANI) ternary hybrid composite synthesized by interfacial polymerization. The composites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), ultraviolet–visible absorption (UV–Vis), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS) and electrical conductivity measurements. The composites exhibited noticeable improvement in electrical conductivity and excellent electrochemical reversibility when compared to bare polymer. The electrochemical properties of the composite electrode are investigated by galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) studies. The enhanced specific capacitance with higher conductivities is observed in PANI/rGO/Fe$^0$ (342 F g$^{-1}$) when compared with PANI (182 F g$^{-1}$) and PANI/rGO composites (294 F g$^{-1}$) with a constant current density of 1.0 A g$^{-1}$. The cyclic stability of the composite, following 500 cycles of operations, was at 68.6 (PANI), 80.6 (PANI/rGO) and 95.4% (PANI/rGO/Fe$^0$) of their initial capacitance. The higher conductivity, higher specific capacitance and cyclic self-stability of PANI/rGO/Fe$^0$ ternary composite can provide new prospects in the field energy storage application.