Hybrid nanofibers with different concentrations of functionalized carbon nanotubes (CNTs) in polyacrylonitrile (PAN) were fabricated using the electrospinning technique and subsequently carbonized. Acrylonitrile-modified CNTs were dispersed in the PAN before electrospinning. The surface morphologies and structures of the nanofibers were characterized by Raman spectroscopy, and scanning and transmission electron microscopy, which showed that the average diameter of the CNT/PAN nanofibers was 110 nm and that the CNTs were embedded in the nanofibers. Raman results indicate that embedded CNTs in the PAN nanofibers nucleate the growth of carbon crystals during PAN carbonization. The lowest sheet resistance of the carbon nanofiber was 8 Omega/sq, and the electromagnetic interference shielding efficiency was about 20 dB.