High-conductivity titanium nitride nanowire can be used as a growth substrate of polyaniline to reduce the charge transfer resistance of the electrode material and improve the supercapacitor behavior of polyaniline. A polyaniline/titanium nitride nanowire (PANI/TiN) was synthesized as a supercapacitor electrode material via seed-assisted hydrothermal process and high-temperature calcinations with flexible carbon fiber as a substrate. PANI/TiN nanowires have a highly ordered coaxial core-shell nanowire structure, and the nanowires split each other to favor the ion diffusion and electron transportation and improve the energy storage performance. PANI/TiN exhibits a higher specific capacitance of 403 F/g at 1 A/g and a higher capacitance retention of 53.4% when the current density increases from 0.5 A/g to 10.0 A/g. The capacitance retention rate of PANI/TiN is 79.1% after 1 000 cycles of charging and discharging at 5 A/g. Compared with PANI, PANI/TiN has the improved electrochemical energy storage properties. The flexible all-solid-state symmetric supercapacitor (i.e., PANI/TiN supercapacitor) was assembled by using PANI/TiN as an electrode. PANI/TiN//PANI/TiN supercapacitor has the specific capacitance of 100.2 F/g at 1 A/g, and there is little attenuation of the specific capacitance after bending at different angles. PANI/TiN//PANI/TiN supercapacitor can obtain an energy density of 50.1 W?偸h/kg at a power density of 500 W/kg. Red light emitting diode (a rated voltage of 1.8 V) can be lighted up by one unit of the supercapacitor, indicating a promising potential application for energy storage.