Bacterial infection has always been a long-term problem of human history and has nowadays became a severe threat to human health with the appearance of drug-resistant bacteria due to the abuse of antibiotics. In this study, a high chlorin e6 (Ce6) photosensitizer-loaded polyethyleneimine-functionalized graphene (PEI-G) nanocomposite (PEI-G@Ce6) was prepared. The loading capacity of Ce6 on PEI-G@Ce6 was approximately up to 32.91 wt%, which was higher than that of other nanomaterials. The as-prepared PEI-G@Ce6 not only improves the photostability of free photosensitizer Ce6 molecules but also maintains the ability of singlet oxygen generation. Based on the dual enhancement of the physical antibacterial effects of PEI-G and the photodynamic therapy (PDT) antibacterial effects of loaded photosensitizer Ce6, PEI-G@Ce6 exhibited enhanced antibacterial efficiency towards Staphylococcus aureus. Therefore, the present strategy provided an effective platform to improve antibacterial efficiency for the better treatment of wound infections.