In this study, photocatalytic activity of Ca-doped ceria (CDC) for malachite green (MG) degradation was investigated. CDC was successfully synthesized via co-precipitation method using ammonium oxalate as a precipitating agent. CDC was characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), UV-Vis spectroscopy, and scanning electron microscopy (SEM). The band gap energy (Eg) of CDC was found to be 3.96 eV. In addition, the factors affecting the photodegradation of MG including; irradiation time, photocatalyst dosage, initial dye concentration, and solution temperature were studied. The results revealed that CDC could degrade approximately 93% of MG dye at the concentration of 6 mg/L, irradiation time of 90 min, photocatalyst dosage of 0.1 g, and solution temperature of 35 °C. The obtained results indicate that CDC is a promising material for the photocatalytic applications and can be used to eliminate very toxic dyes such as MG.