Four nanocomposite samples of polyaniline/nano titanium dioxide/activated carbon (PANI/nTiO₂/AC) via ex situ and in situ polymerization methods are prepared and optimized for electrochemical analysis in three different electrolytes, i.e., acidic H₂SO₄, basic KOH, and neutral Na₂SO₄. The results indicate that PANI/nTiO₂/AC (PTA2) has a good, interconnected network. The presence of TiO₂ nanoparticles promotes the faradaic capacitance, and AC also provides a large surface area for proficient redox reactions. The electrochemical performances of the ternary nanocomposite electrode material are examined by cyclic voltammetry, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy test with three different electrolytes, i.e., acidic (0.1 m H₂SO₄), basic (0.1 m KOH), and neutral (0.1 m Na₂SO₄) aqueous electrolytes. The results reveal that present device attains maximum specific capacitance value 827 F g⁻¹ at 10 mV s⁻¹ in 0.1 m H₂SO₄ for PTA2 supercapacitor device and shows 72% retain specific capacitance from initial value of specific capacitance after 10 000 GCD cycle. Moreover, it also exhibited maximum energy density of 37 Wh kg⁻¹ at 0.5 mA cm⁻² with maximum specific power of 1332 W kg⁻¹. The reason may be attributed to increased π–π conjugated system for PANI with titanium dioxide nanoparticles and AC for providing an effective surface area (343 m² g⁻¹) for the electrolyte ions to penetrate inside the electrode material and also furnishing efficient diffusion of electrolyte ions in PANI matrix. PTA2 ternary nanocomposite shows more thermal stability than PANI alone. It enhances the overall supercapacitive performance of the supercapacitor device (PTA2 device), which is a symbolic improvement compared to reported articles.