ABSTRACT Polymethyl methacrylate (PMMA) has been widely used in stomatology to prepare denture bases. However, issues such as a porous structure and high water absorption rate facilitate bacterial growth. This study aimed to synthesize silver nanoparticle/graphene oxide (AgNPs/GO) composites by the chemical reduction method, which was mixed with PMMA by the ball milling method to improve the antibacterial properties of PMMA. Scanning electron microscopy and transmission electron microscopy showed that AgNPs were uniformly dispersed on the GO sheets. AgNPs/GO composite and GO were investigated using x-ray diffraction. The modified AgNPs/GO/PMMA composite demonstrated enhanced antibacterial properties against Streptococcus mutans based on the film adhesion test. Also, the number of bacteria decreased and the morphology of bacteria changed with the increase in mass fraction. Besides, the improved mechanical properties were confirmed by the friction and contact angle tests. Moreover, the composite did not induce cytotoxicity in human gingival mesenchymal stem cells.