Free-standing nanocomposite films of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/Fe₃O₄ were successfully prepared by mechanically blending magnetic Fe₃O₄ nanoparticles with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution and casting the mixed solution on polypropylene film substrates. The characterization of nanocomposite films was investigated by scanning electron microscopy and Fourier transform infrared spectra. The result indicated that the Fe₃O₄ nanoparticles were composited together well with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate). It was found that the content of Fe₃O₄ has a significant effect on the electrical conductivity of the nanocomposite film. The maximum electrical conductivity could be up to 218 S/cm, at optical weight ratio (25 wt% Fe₃O₄). Simultaneously, the Seebeck coefficient fluctuated smoothly in a tiny range (13.1–15.8 µV/K), and the power factor was calculated to be 5.26 μW/mK².