This study focuses on the synthesis of Polyaniline (PANI), graphene oxide (GO), and their nanocomposites with metal oxides (MO) and hexagonal boron nitride (h-BN) for their application in the supercapacitor. In this study, PANI/GO, PANI/GO/TiO2, PANI/GO/MoS2 and PANI/GO/h-BN ternary nanocomposites were synthesized following a chemical oxidative polymerization method. The prepared nanocomposites were characterized by FTIR, XRD, TGA, SEM and electrochemical analysis. The electrochemical properties of the nanocomposites were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical polarization and impedance analysis. CV profile of the nanocomposite showed that incorporation of GO, MO and h-BN in the polyaniline backbone improved capacitance, energy density and power density significantly. Among the synthesized ternary nanocomposites, PANI/GO/h-BN showed highest capacitance of 946 F/g and high capacitance retention after 100 cycles of charging and discharging. Finally, a set of hybrid asymmetric supercapacitors were constructed using the synthesized nanocomposites as positive electrode and activated carbon as negative electrode. The device was assessed following the GCD method. The supercapacitor device with PANI/GO/h-BN nanocomposite as positive electrode exhibited higher specific capacitance of 351 F/g with high power density of 4500 W/kg, and it lit up a 5 mm LED for 243 min, indicating its superiority over other electrodes.