Indirubin is primarily known for its biological activity, especially in the field of medicine and pharmacology. It has been studied extensively for its potential anti-cancer properties, showing inhibitory effects on various cancer cell lines by interfering with cell cycle progression and inducing apoptosis. One of its key mechanisms involves the inhibition of cyclin-dependent kinases (CDKs) and glycogen synthase kinase-3 (GSK-3), which are enzymes involved in cell division and signaling pathways. It also exhibits anti-inflammatory and immunomodulatory effects, making it a candidate for research in treating autoimmune and inflammatory diseases. Additionally, indirubin and its derivatives have been explored in the treatment of chronic myelogenous leukemia (CML), particularly in traditional medicine formulations like Danggui Longhui Wan, which has been used in Chinese medicine. Due to its ability to cross the blood-brain barrier, there is growing interest in its potential neuroprotective effects and application in neurodegenerative disorders such as Alzheimer’s disease. However, its clinical use is limited by poor solubility and bioavailability, prompting ongoing research into analogs and delivery systems to enhance its therapeutic effectiveness.