A receptor-targeting AIE photosensitizer (CE-TPA) is synthesized by conjugating cephalothin with a cationic D-A type AIE photosensitizer for selective killing of Gram-positive bacteria over Gram-negative bacteria and normal mammalian cells. By virtue of the strong photosensitization capability, CE-TPA exhibits efficient killing against Gram-positive methicillin-resistant Staphylococcus aureus. More importantly, the photodynamic bactericidal outcome can be conveniently reflected in a real-time fashion by the polarity-sensitive property of CE-TPA.