Monoclinic vanadium dioxide (VO₂ (M)) particles co-doped with niobium and tungsten, with potential application in smart windows, were synthesized by hydrolysis and subsequent thermal decomposition of vanadyl sulfate. All the doped VO₂ particles exhibited a monoclinic crystalline phase and the critical phase transition temperature (Tc) of VO₂ (M) was adjusted by Nb and W co-doping. The Tc of Nb-doped VO₂ (M) decreased at a rate of approximately 10 °C/at% Nb dopant, and the transition temperature could also be accurately controlled to room temperature (about 27 °C) by co-doping with Nb and W. A film prepared using co-doped VO₂ (M) particles showed a solar modulation ability of ~18% and a luminous transmittance of 40%, indicating that the co-doped VO₂ (M) particles represent suitable candidates for smart window applications.