We have demonstrated here a facile gamma-irradiation induced direct fabrication of Ag nanoparticles on glass substrates for SERS applications. It has been found that the agents complexing with the Ag⁺ ions play a dominant role in enabling Ag particle growth directly on the glass substrates, whereas using bare AgNO₃ solution only produced Ag particles in the solution but not on the glass substrate. Moreover, the complexing agent also decides the size and morphology of the Ag nanoparticles, where using ammonia leads to much larger Ag particles than when using ethylenediamine. The γ-ray dose can also influence the size of the Ag nanoparticles, and a higher dose usually results in larger Ag nanoparticles. The SERS performances of the as-fabricated Ag nanoparticles supported on glass substrates have been compared. The uniform Ag nanoparticles with smaller sizes prepared by using ethylenediamine as the complexing agent typically present superior SERS sensitivities. We believe that this facile and cost-effective gamma-irradiation induced fabrication of Ag nanoparticles will be of interest in SERS studies.