The impact of the microwave annealing (MA) on the crystallinity and on the electrical properties of CeO2 thin films has been investigated by Raman Spectroscopy, capacitance–voltage (C–V) measurements and current–voltage (I–V) measurements. This paper highlights the influence of the temperature, time, and atmosphere used for the MA on the crystallinity, the surface quality, and the oxidation state of Ce of CeO2 thin films. At the same time, the impact of microwave annealing on the flatband voltage (VFB) and the interface traps density (Dit) is studied by C–V measurements. Moreover, the leakage current is compared before and after the microwave annealing. Therefore, this paper shows a sharp improvement of the CeO2 film crystallinity and a decrease in leakage current after a microwave annealing performed at 900 °C for 5 min under nitrogen atmosphere. To our knowledge, it is the first time that the impact of MA on CeO2 films is reported.