Formation of Ag-Au nanoalloy and self-organization of Ag nanoparticles into nanostructured wires under UV irradiation were reported in this work. This phenomenon was observed only in the presence of chloroauric acid. On the basis of the analysis of transmission electron microscope images and energy-dispersive X-ray spectroscopy, formation mechanism of nanostructured wires as well as of Ag-Au nanoalloy were proposed. The role of UV illumination and the presence of chloride ions were discussed. The UV-Vis spectra confirm that the synthesized material has one absorption band at 530 nm, which was related to the presence of Ag-Au nanoalloy. Moreover, the Ag-AgCl nanocomposite, in which Ag NPs are located on the edges of AgCl cubes, was successfully synthesized by the modified method.