In this paper, silver (Ag) nanoclusters-loaded graphitic carbon nitride (g-C 3 N 4 ) nanosheets are synthesized and their physical properties as well as photocatalytic activities are systematically investigated by different techniques. The existence of Ag atoms in the form of nanoclusters (NCs) rather than well-crystallized nanoparticles are evidenced by X-ray diffraction patterns, SEM images, and XPS spectra. The deposition of Ag nanoclusters on the surface of g-C 3 N 4 nanosheets affect the crystal structure and slightly reduce the band gap energy of g-C 3 N 4 . The sharp decrease of photoluminescence intensity indicates that g-C 3 N 4 /Ag heterojunctions successfully prevent the recombination of photo-generated electrons and holes. The photocatalytic activities of as-synthesized photocatalysts are demonstrated through the degradation of rhodamine B (RhB) solutions under Xenon lamp irradiation. It is demonstrated that the photocatalytic activity depends strongly on the molar concentration of Ag + in the starting solution. The g-C 3 N 4 /Ag heterojunctions prepared from 0.01 M of Ag + starting solution exhibit the highest photocatalytic efficiency and allow 100% degradation of RhB after being exposed for 60 min under a Xenon lamp irradiation, which is four times faster than that of pure g-C 3 N 4 nanosheets.