In this paper, silicon carbide/carbon (SiC/C) hybrid nanofibers were synthesized via electrospinning and high-temperature pyrolysis. As-prepared nanofibers possess a high aspect ratio and a scaly surface. The electromagnetic (EM) parameters and EM wave absorption properties of the SiC/C composite nanofiber were studied focusing on the polarization loss mechanism and on the impedance matching in the range from 2 GHz to 18 GHz. The 30 wt% composite nanofibers in the paraffin matrix show satisfactory dielectric loss value and a minimal reflection loss (RL) of approximately −36 dB at 6.8 GHz with a 3 mm thickness. Moreover, the maximum effective absorption (<−10 dB) bandwidth (EAB) is approximately 4.1 GHz (12.6–16.7 GHz) with a 1.5 mm thickness, which could cover most of the Ku-band. The above results show that the prepared carbon-rich SiC nanofiber-filled composite is a promising EM wave absorbing material with excellent EM wave absorbing ability.