Bile salts, a class of steroidal biosurfactants, play critical roles in lipid digestion and absorption, as well as the regulation of glycolipid metabolism. Their unique molecular structure confers them intriguing aggregation properties and assembly behaviors, distinct from those of classical surfactants. By forming micelles, they facilitate lipid digestion and maintain metabolic homeostasis. In addition, bile salts enhance drug dissolution and absorption through the formation of phospholipid mixed micelles, leveraging their biocompatibility for widespread use as drug absorption enhancers. However, the structure and assembly mechanism of bile salt micelles remain subjects of ongoing debate. This article introduces the molecular structure and aggregation properties of bile salts, as well as the analytical methods for their micellar structures. It summarizes the research progress on the structures of simple bile salt micelles and mixed micelles, and finally, discusses the physiological significance and potential clinical applications of bile salt micelles. Elucidating the structure of bile salt micelles is not only essential for deepening the understanding of their physiological roles, but also provides a theoretical basis for the prevention and treatment of metabolic diseases (e.g., obesity, cholestasis), and supports their innovative applications in fields such as nanodrug delivery.