Bacterial keratitis (BK) is one of the most threatening ocular diseases, leading to stromal injury, corneal perforation, or even blindness. Avoiding side effect is necessary for efficient BK treatment. Herein, we develop GDY-Ag@AgCl heterojunction catalysts to achieve BK treatment via mild phototherapy strategy. Mild photothermal therapy (PTT) can greatly enhance the generation of ROS produced by photocatalytic therapy (PCT), which can decrease the dosage of photosensitizer, as well as solve the issue of uncontrolled local overheating and the accumulation of PTT agents, minimizing side effects and avoiding secondary injuries. The results demonstrate that lower dosage of PTT/PCT agents, and milder and controlled thermal effect of GDY-Ag@AgCl exhibits excellent inactivation performance against ampicillin-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Moreover, this phototherapy strategy not only achieves more effective treatment of BK induced by MRSA with no side effects but also shows a superior ability to alleviate inflammation. This strategy offers a safe and promising theragnostic approach for treating ocular drug-resistant bacterial infections.