Cerium oxide nanoscale particles (NPs) were synthesized by homogeneous precipitation method, and were subsequently characterized by using thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), X Ray Diffraction (XRD), Scanning Electron Microscope coupled with Energy dispersive X-ray (SEM-EDX), UV–vis diffuse reflection (UV-vis DRS), Fourier transform infrared (FTIR) and (Isoelectric point (IEP) techniques as well as theoretical calculations based on density functional theory (DFT). The as-prepared CeO₂ catalyst was assessed for photodegradation of Indigo Carmine (IC) dye under two sources of irradiation (UVA 368 nm and white light-emitting diode: LED 50 W). Powder XRD revealed the formation of crystalized cubic phase CeO₂ NPs with average crystallite size of ~9 nm. CeO₂ NP sample exhibited significant specific surface area (158.17 m²/g) and relatively lower band gap (3.1 eV vs 3.15) than bulk CeO₂. SEM analysis showed spherical-like in shape NPs with strong agglomeration of CeO₂ NPs. EDX confirmed the stoichiometry of CeO₂ NPs. IEP of CeO₂ NPs was found to be 7.2. Under LED 50 W-light irradiation, 87.80% of IC was removed within 60 min, which was 1.5 times superior than that achieved under UVA-light illumination (63.41%). Pseudo-first-order kinetic model gave the best fitting. Appropriate mechanisms were suggested for the degradation of IC dye under UVA- and LED-light irradiations based on the photocatalytic responses and the energy band diagram position data of CeO₂ NPs.