Corroles have been previously demonstrated to be a new and promising photosensitizer (PS) in photodynamic therapy (PDT) for cancer cells. This research reported the preparation of an electron-deficient flat gallium(iii) tris(ethoxycarbonyl)corrole (1-Ga). Its in vitro PDT activities towards different cancer cell lines were examined, and the best PDT activity was observed in A549 cell lines. 1-Ga could penetrate the cell membrane rapidly and exhibit remarkable photo-cytotoxicity. 1-Ga can induce A549 cell apoptosis via ROS-mediated mitochondrial pathways, in which p38 and sirt-1 proteins play a key role. A PTD test in vivo showed that 1-Ga can significantly reduce the growth of A549 xenografted tumor cells without an obvious loss of mice weight upon PDT treatment.