Photodynamictherapy(PDT) has attracted much attention in disease treatments. However,theexploration of a novel methodfortheconstruction of outstandingphotosensitizers(PSs)withstimuli-responsiveness remains challenging. In this study, we,forthefirst time, report a novel and effective strategytoboostreactive oxygen species (ROS) generation bybridgingdonor-acceptor (D-A)typePSswiththeazogroup. In contrasttothecounterpart withoutazo-bridging,theazo-bridged PSs exhibit remarkably enhanced ROS generation via bothtype-I andtype-II photochemical reactions. Theoretical calculations suggest thatazo-bridgingleadstoa prominent reduction in Delta E-ST, thereby enabling enhanced ROS generation viaefficientintersystemcrossing(ISC).Theresultingazo-bridged PS (denoted asAzo-TPA-Th(+)) exhibits a particularly strong bactericidal effect against clinically relevant drug-resistant bacteria,withthekilling efficiency upto99.999999% upon white light irradiation. Sinceazo-bridginggenerates an azobenzene structure,Azo-TPA-Th(+) can undergo trans-to-cis isomerization upon UV irradiationtoform emissive aggregates by shutting downtheISC channel. By virtue ofthefluorescence turn-on property of unboundAzo-TPA-Th(+), we propose a straightforward methodtodirectly discerntheeffectivephotodynamicbactericidal dose without performingthetedious plate-counting assay. This study opens a brand-new avenueforthedesign of advanced PSswithboth strong ROS generation and stimuli-responsiveness, holding great potential in high-quality PDTwithrapid prediction ofthetherapeutic outcome.