Nb-Doped LiNi0.4Co0.2Mn0.4O2 (Nb-NCM) nanobelts have been successfully fabricated for the first time through a facile electrospinning method by the delicate control of PAN pyrolysis and Nb-NCM formation (including nucleation and subsequent growth processes). According to the experimental evidence from temperature-dependent characterization and isolation of the intermediates, the formation of nanobelts undergoes a morphology evolution from nanofibres to nanotubes, and finally to the nanobelts composed of subunit nanoparticles. When used as a cathode for lithium-ion batteries, the as-electrospun Nb-NCM nanobelts exhibit superior electrochemical performances, which could be attributed to their unique features, such as their 1D nanostructure, well-crystallized nature and Nb-doping. These features can improve the ionic conductivity of Nb-NCM nanobelts and stabilize the electrode/electrolyte interface. Therefore, the 1D Nb-NCM nanobelts developed in this study not only provide an excellent model to investigate the fabrication of multi-element oxides using the electrospinning method, but also open up a facile route for designing 1D layered cathodes with a complex component for high performance lithium-ion batteries.