Electroactive composite films of carbon nanotubes/polyaniline/nickel hexacyanoferrate (CNTs/PANI/NiHCF) were synthesized on platinum substrates modified with CNTs by a one-step co-polymerization using cyclic voltammetry. The composite films were characterized by Fourier transforminfrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscope (EIS) methods were used to study the cycling stability and the electrochemical capacitive performance of the CNTs/PANI/NiHCF films. Results showed that three-dimensional porous network composite films with uniform distributions of PANI and NiHCF nanoparticles on the CNTs were formed by this new method. The specific capacitance of the inorganic-organic hybrid films were 262.28 F·g-1 with a specific energy of 29.51 Wh·kg-1 at a current density of 2 mA·cm-2. The specific power was 10228.61 W·kg-1 at a current density of 10 mA·cm-2. Meanwhile, CNTs/PANI/NiHCF films showed a capacity decay of only 19.92% after 2000 charge/discharge cycles and had a coulombic efficiency of over 99%. Therefore, the composite films exhibit outstanding power performance, fast dynamics of charge transport and are excellent materials for use in supercapacitors.