Photodegradable photosensitizers have gained significant attention in recent years due to their potential advantages in photodynamic therapy. By degrading upon light exposure, these photosensitizers reduce post-treatment drug residues, minimize toxicity, and enhance the safety and precision of therapy. This review provides an overview of the design and current applications of photodegradable photosensitizers, addressing challenges related to light absorption efficiency, toxicity of degradation products, and tissue penetration. Furthermore, future optimization strategies, including chemical modifications, nanocarrier integration, and combination therapies, are discussed.