The problems of severe oxygen-dependent hypoxia and fluorescence aggregation-caused quenching (ACQ) of conventional photosensitizers (PSs) in tumour cells with a hypoxic microenvironment have impeded the development of photodynamic therapy (PDT) for cancer treatment. To overcome these shortcomings, PDT PSs based on free radical reactive oxygen species (ROS) with aggregation-induced emission (AIE) characteristics have attracted considerable attention recently. Herein, we design and synthesize two AIE-PSs, OMEPY and OMEPYH, based on the benzophenone core. Detailed photophysical and photochemical study has shown that these two AIE-PSs produce ROS based on both type I (electron transfer) and both type II (energy transfer) pathways. The in vitro experimental results reveal that OMEPYH can be used for mitochondria-targeted PDT due to the interaction of its positively charged methylpyridinium group with the negative mitochondrial membrane via electrostatic interactions. This work provides a strategy for utilizing the benzophenone core to design efficient AIE-PSs for the image-guided PDT modality.