We report a facile method for the fabrication of spongelike gold/amino acid nanocomposites by the addition of NaBr to glutamic acid-stabilized gold nanoparticles (GNPs) at room temperature. The gold/glutamic acid (Glu) nanocomposite is characterized by TEM, SEM, UV-vis spectroscopy, and XRD measurements. The results suggest that the three-dimensional spongelike gold/Glu nanocomposites with mean diameter of 50 nm are formed via the nanospheres fusing into one another. The driving force for the fabrication of spongelike gold/amino acid nanocomposites is the van der Waals attractive forces of Br- partially coated GNPs. Furthermore, the obtained spongelike gold nanocomposites can be used as surface-enhanced Raman scattering (SERS) substrates with high SERS activity and stability for detecting Rhodamine 6G (R6G) molecules. Hence, NaBr-mediated preparation of SERS substrates described in this work has potential applications in chemical and biological analysis as well as medical detection.