Vine-like polyaniline (PANI) nanostructures were prepared using electrochemical polymerization on activated carbon nanofibers (ACNF) in order to use as a supercapacitor. Electrospun polyacrylonitrile (PAN)-based nanofibers were firstly carbonized and physically activated to increase the specific surface area. The PANI formed a vine-like shape and well-contacted with the surface of ACNF. The remarkably improved electrochemical performances of PANI-deposited ACNF electrode were investigated using cyclic voltammetry (CV) and galvanostatic charge/discharge test, and electrochemical impedance analysis. The current area of the PANI-ACNF electrode is higher than that of ACNF electrode in CV curves and the specific capacitance of the PANI-ACNF was 832Fg−1 which is much higher than 353Fg−1 of ACNF at a current density of 1Ag−1 in galvanostatic charge/discharge analysis. During galvanostatic charge/discharge test of 1000 cycles at 1Ag−1, the PANI-ACNF sample keeps its specific capacitance up to the value of 765Fg−1 (92% retention). Also, the PANI nanostructure on the ACNF substrate achieved a rapid doping/dedoping process between the surface of electrode and electrolyte ions in comparison with ACNF electrode.