In this study, silver nanoparticles (Ag NPs) were generated, functionalized, and stabilized using a one-step photochemical approach that does not require more than few minutes with a low power near UV LED source. A series of thiol-functionalized thioxanthone (TX) derivatives were prepared and used for the photoinduced synthesis of Ag NPs and their surface functionalization and stabilization. Upon illumination, Ag+ ions are reduced by free radicals generated through an oxidoreductive process occurring between excited TX groups and N-methyldiethanolamine. This process generates monodispersed silver nanoparticles with an average diameter about 2-7 nm depending on the TX derivative used. Due to the strong interaction between Ag atoms and thiol groups of the ligands, AgNPs are capped in situ by TX derivatives and exhibit remarkable stability in solution. Subsequent studies carried out on silver NPs/TX nanoassemblies (designed as AgNPs@S-TX) demonstrated their potentials in free radical photopolymerization of acrylate monomers.