Li2MnSiO4 has been considered as a promising cathode material with an extremely high theoretically capacity of 332 mAh g−1. However, due to its low intrinsic conductivity and poor structural stability, only about half of the theoretical capacity has been realized in practice and the capacity decays rapidly during cycling. To realize the high capacity and improve the cycling performance, Li2Mn0.8Fe0.2SiO4/carbon composite nanofibers were prepared by the combination of iron doping and electrospinning. X-ray diffraction, scanning electron microscope, and transmission electronic microscope were applied to characterize the Li2Mn0.8Fe0.2SiO4/carbon nanofibers. It was found that Li2Mn0.8Fe0.2SiO4 nanoparticles were embedded into continuous carbon nanofiber matrices, which formed free-standing porous mats that could be used as binder-free cathodes. The iron doping improved the conductivity and purity of the active material, and the carbon nanofiber matrix facilitated ion transfer and charge diffusion. As a result, Li2Mn0.8Fe0.2SiO4/carbon nanofiber cathodes showed promising improvement on reversible capacity and cycling performance.