Three representative noble metal (Ag, Au and N) nanoparticles decorated graphene oxide (NMNPs/GO) composites were fabricated via gamma-irradiation without scavenger. The NMNPs/GO composites exhibited the pure and well-dispersed particles structure, which directly illustrated that the GO could be acted as scavenger to benefit reduction and growth of NMNPs. Compared with irradiated GO (IGO), the GO substrate of composites had the lower relative content of hydroxyl groups, meanwhile, the relative contents of carbonyl groups (N > Au > Ag) were increased with increasing valence of noble metal. Such results illustrated that the abundant hydroxyl groups could convert the hydrated electrons, hydroxyl and hydrogen radicals to promote the growth of NMNPs on the surface of GO. In addition, the Raman signals of Ag NPs/GO composites were significantly enhanced (6.18 fold more than pristine GO, respectively), exhibiting obvious surface-enhanced Raman scattering activity. Therefore, this paper revealed that the GO could convert the hydrated electrons and radicals to synthesizing NMNPs/GO composites during gamma-ray irradiation.