 In this study, the electrochemical performance of a polyaniline-based porous ternary composite (PNHFeG) electrode material is reported for a high-performance supercapacitor. The PNHFeG ternary composite was prepared through in situ oxidative polymerization of aniline in the presence of a binary composite NHFeG that involves the combination of flower-like nanostructured Ni(OH)2 and iron oxide-doped reduced graphene oxide (Fe-RGO). The porous ternary PNHFeG composite with high surface area (239 m2 g−1) notably exhibits maximum specific capacitance (Csp) of 2714 F g−1 at 5 A g−1 current density, along with 98.5% retention of its initial capacitance even after 2000 cycles. Moreover, even at a higher current density of 30 A g−1, the composite electrode material maintains a remarkable Csp value of 1223 F g−1. Finally, the PNHFeG electrode material reveals a power density of 1498 W kg−1, along with a maximum energy density of 135.7 Wh kg−1 at 5 A g−1, suggesting that the current composite electrode material can be considered as a promising candidate for high-performance supercapacitor applications.