ZrO₂ nanorods with different dispersibility were prepared via a facile microwave-hydrothermal approach in the absence of any organic modifier. XRD, TEM, HRTEM, N₂ adsorption窶電esorption measurements (BET) and XPS were used to characterize the microstructure of as-prepared ZrO₂ nanorods, and a possible mechanism was proposed to explain the formation and evolution of ZrO₂ nanorods under microwave irradiation. The concentration of zirconium precursor was found to significantly affect the dispersion of ZrO₂ nanorods, and the lower concentration of zirconium precursor favors the formation of ZrO₂ nanorods with higher dispersibility under microwave irradiation. The as-prepared ZrO₂ nanorods were further used to estimate their potential application as a humidity sensor. The sample with a higher concentration of surface oxygen vacancies exhibits a higher humidity sensor response due to more active sites for water adsorption, and the humidity sensing mechanism of ZrO₂ nanorods was also discussed by complex impedance spectra in detail.