Nitrogen-doped carbon nanofibers (CNFs) were synthesized using a facile electrospinning technique with the addition of urea as a nitrogen-doping agent. The amount of urea was selectively adjusted to control the degree and effectiveness of N-doping. The morphology of N-doped CNFs was investigated by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, whereas their electrochemical performance was studied using cyclic voltammetry and galvanostatic charge-discharge experiments. The nitrogen content of N-doped CNFs increased significantly from 11.31% to 19.06% when the doping amount of urea increased from 0% to 30%. N-doping also played an important role in improving the electrochemical performance of the CNFs by introducing more defects in the carbon structure. Results showed that N-doped CNFs with the highest nitrogen content (19.06%) exhibited the largest reversible capacity of 354 mAhg(-1) under a current density of 50 mAg(-1); and when the current density was increased to 1 Ag-1, a capacity of 193 mAhg(-1) was still maintained. It is, therefore, demonstrated that N-doped CNFs have great potential as suitable sodium-ion battery anode material.