An easy and cost-effective route is demonstrated to grow spongy-network-like polyaniline (SpN-PANI) thin films on stainless steel (SS) by galvanostatic electrodeposition. Through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) characterizations, the physicochemical properties of the SpN-PANI thin films were fine-tuned for supercapacitor application. The hydrophilic nature of SpN-PANI thin films was examined by using contact angle measurements. Next, the capacitive behavior of the SpN-PANI thin film was assessed by using cyclic voltammetry (CV), galvanostatic charging-discharging (GCD), and electrochemical impedance spectroscopy (EIS). Specifically, these results show that SpN-PANI thin films can exhibit a maximum specific capacitance of 580 F.g⁻¹ at a scan rate of 5 mV.s⁻¹ in a 0.5 M Na₂SO₄ electrolyte solution, as well as superior cycling stability (84% capacity retention after 1000 cycles). Thus, the strategy presented here can be applicable to produce a SpN-PANI-based thin film which has prospects as an active electrode material for supercapacitor devices.