In this report, we fabricate spherical cerium oxide (CeO2) nanoparticles by simple wet chemical method. Utilizing X-ray diffraction (XRD), the crystallinity was investigated. Hexagonal structure of the unit cell was found in the XRD study. The morphology of the fabricated nanoparticles was investigated using Field emission Scanning Electron Microscope (FESEM). Optical band gap was calculated by using UV-Vis spectra. The partial/complete mineralization of organic dye can be utilized using semiconductor nano-photocatalyst. Here, photocatalytic activity of the fabricated CeO2 was explored by the degradation of methylene blue (MB) dye using visible light irradiation. Different operational parameters e.g. initial dye concentration, catalyst doses and pH and their effect on photodegradation was also studied.