Discovering potent antibiotics is of critical importance due to the substantial increases of microbial resistance. Xanthones are intriguing sources of antimicrobials, despite a scarcity of extensive investigations into their mechanisms of action. Here, we reported the development of a series of xanthone derivatives, among which compound XT17 displayed strong broad-spectrum antibacterial activity, weak hemolytic activity, and low cytotoxicity against mammalian cell lines, low frequencies of drug resistance, and potent in vivo efficacy in Staphylococcu aureus – or Pseudomonas aeruginosa –induced murine corneal infection models. Compound XT17 presented a multifaceted mode of actions, involving the disruption of cell wall by interacting with lipoteichoic acid or lipopolysaccharides and the suppression of DNA synthesis. A further docking study confirmed the capability of compound XT17 to form a stable complex with the bacterial gyrase enzyme. This work could offer an innovative design strategy for developing broad-spectrum therapeutic agents against drug-resistant bacteria.