Periodontitis, a leading cause of adult tooth loss and linked to various systemic diseases, is promoted by subgingival plaque biofilms, with Streptococci as early colonizers responsible for surface adhesion. Current studies of Streptococci adhesion have focused on bacteria surface adhesins with acquired protein membranes on the tooth surface, yet no critical proteins with implications for the overall early adhesion of subgingival plaque have been reported. Here, we identified that the "Barrel-like adhesion domain" of streptococcal EF-Tu facilitates cell-surface attachment, promotes biofilm formation, and contributes to the development of periodontitis. In the adherent state, EF-Tu is transported from the cytoplasm to the cell surface through membrane vesicles. Furthermore, we first found that simeprevir, an FDA-approved drug, binds to the "Barrel-like adhesion domain" of EF-Tu and effectively inhibits the protein's surface adhesion and secretory pathways. Simeprevir showed the ability to inhibit dental plaque formation and provided prevention and treatments for periodontitis.