Infections involving methicillin-resistant Staphylococcus aureus present great challenges, especially when biofilms and persister cells are involved. In this work, an α/β chimeric polypeptide molecular brush (α/β CPMB) is reported to show excellent performance in inhibiting the formation of biofilms and eradicating established biofilms. Additionally, the polymer brush efficiently killed metabolically inactive persister cells that are antibiotic-insensitive. Antimicrobial mechanism studies showed that α/β CPMB causes membrane disturbance and a substantial increase in reactive oxygen species (ROS) levels to kill bacteria, and mesosome-like structure formation was also observed. Furthermore, the polymer brush was able to kill clinically isolated multidrug resistant Gram-positive bacteria with no risk of antimicrobial resistance. The α/β CPMB has demonstrated great potential in addressing the great challenge of eradicating multidrug resistant Gram-positive bacterial infections.