Layered 2D molybdenum disulfide (MoS₂) and Ce-doped MoS₂ nanostructures were synthesized by the hydrothermal method. X-ray diffraction patterns reveal the hexagonal symmetry of MoS₂ nanostructures. The X-ray photoelectron spectroscopy confirmed the presence of Ce ions in MoS₂ nanostructures with a significant peak shift. Morphological analysis confirms the formation of layered MoS₂ nanosheets. The effect of Ce ions in MoS₂ nanostructures was investigated against methylene blue (MB) under visible light irradiation. 5 mM Ce-doped MoS₂ exhibits 99.36% of degradation efficiency against MB under visible light irradiation. The effective suppression of electron–hole pairs enhances the degradation efficiency upon the introduction of Ce ions in the MoS₂ matrix. A possible charge transfer mechanism has been proposed.