Different niobium (Nb)-doped tungsten oxide (WO3) nanowire films were prepared by magnetron sputtering and hydrothermal methods, and their performances were analyzed. The experimental results revealed that Nb doping caused the tungsten oxide nanowire structure to become loose, increased the interplanar spacing, and raised the oxygen vacancy concentration, significantly improving the electrochromic properties. However, with increasing Nb doping levels, the cyclic stability of the samples decreased, possibly due to lattice distortion induced by Nb. The analysis demonstrated that the sample doped with 0.5% Nb exhibited optimal electrochromic performance and displayed a 5.68% coloring transmittance and an 83.3% optical modulation range at a wavelength of 633 nm. This study elucidated the influence of Nb doping on the electrochromic properties of WO3 nanowire films.