Abstract: Toosendanin (TSN), a tetracyclic triterpenoid derived from Melia toosendan and M. azedarach, demonstrates broad application prospects in cancer treatment. Although previously employed as a pesticide, recent studies have revealed its potential therapeutic value in treating various types of cancer. TSN exerts an anticancer effect via mechanisms including proliferation inhibition, apoptosis induction, migration suppression, and angiogenesis inhibition. However, TSN’s toxicity, particularly its hepatotoxicity, significantly limits its therapeutic application. This review explored the dual nature of TSN, evaluating both its anticancer potential and toxicological risks, emphasizing the importance of balancing these aspects in therapeutic applications. Furthermore, we investigated the incorporation of TSN into novel therapeutic strategies, such as Proteolysis-targeting chimeras (PROTAC) technology and nanotechnology-based drug delivery systems (DDS), which enhance treatment efficacy while mitigating toxicity in normal tissues.