: A simple microwave-assisted (MWI) wet chemical route to synthesize pure anatase phase titanium dioxide (TiO₂) nanoparticles (NPs) is reported here using titanium tetrachloride (TiCl₄) as starting material. The as-prepared TiO₂ NPs were characterized by electron microscopy, X-ray diffraction, UV/visible absorption spectroscopy, and infrared and Raman spectroscopic techniques. Further modification of the anatase TiO₂ NPs was carried out by incorporating plasmonic silver (Ag) NPs and graphene oxide (GO) in order to enhance the visible light absorption. The photocatalytic activities of the anatase TiO₂, Ag/TiO₂, and Ag/TiO₂/GO nanocomposites were evaluated under both ultraviolet (UV) and visible light irradiation using phenol as a model contaminant. The presence of Ag NPs was found to play a significant role to define the photocatalytic activity of the Ag/TiO₂/GO nanocomposite. It was found that the Ag performed like a sink under UV excitation and stored photo-generated electrons from TiO₂, whereas, under visible light excitation, the Ag acted as a photosensitizer enhancing the photocatalytic activity of the nanocomposite. The detailed mechanism was studied based on photocatalytic activities of Ag/TiO₂/GO nanocomposites. Therefore, the as-prepared Ag/TiO₂/GO nanocomposite was used as photocatalytic materials under both UV and visible light irradiation toward degradation of organic molecules.