In this study, considering the good optical properties of CeO2 thin films, their anti-reflective effect on crystalline silicon solar cells was investigated. First molarity and then coating speed optimizations were carried out for the optimum thickness value. In addition, annealing temperature and annealing time optimizations were performed on CeO2 thin films, and the appropriate values for annealing temperature and annealing time were determined. As a result of all optimizations, it was found that 0.3 M concentration, 6000 rpm coating speed, 400 °C annealing temperature, and 120 min annealing time were optimum values for CeO2 thin films. The average reflectance value of CeO2 thin films obtained using these values was 14.32%, while the minimum reflectance value was 0.62%. When the optimum reflectance values were applied to c-Si solar cells with Afors-het simulation, it was observed that the efficiency value increased from 11.57 to 16.89% compared to the uncoated solar cell.