A novel reduced graphene oxide/poly(1,5-dihydroxynaphthalene)/TiO2 (RGO/PDHN/TiO2) ternary nanocomposite conducting polymer is electrochemically synthesized on gold electrodes for supercapacitor applications. The RGO/PDHN/TiO2 nanocomposite polymer film is characterized by field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectra (FT-IR), and energy dispersive X-ray spectrometry (EDX) and X-ray diffraction (XRD). The electrochemical performance of the nanocomposite polymer-modified electrode in 1.0 M HClO4 is investigated by various electrochemical methods such as cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS). The RGO/PDHN/TiO2 nanocomposite polymer film in a three-electrode system exhibits a large specific capacitance of 556 F g−1 in comparison with those obtained using RGO/PDHN (432 F g−1) and PDHN (223 F g−1) at a current density of 2.4 A g−1. Simultaneous usage of the electrical double layer capacitance (EDLC) of RGO with the pseudocapacitive behavior of PDHN and TiO2 results in the large specific capacitance in RGO/PDHN/TiO2. The electrochemical self-stabilities of RGO/PDHN/TiO2, RGO/PDHN, and PDHN polymer films are investigated by continuous cycling between −0.20–0.45 V. The RGO/PDHN/TiO2 nanocomposite yields longer self-stability than that of other polymers after 1700 cycles and maintains about 74% of the initial capacitance values.