Abstract: Okara (soybean residue), a byproduct of soybean processing, is rich in dietary fiber, proteins, phytohormones, and various vitamins. Microbial fermentation enhances the functional components of okara while improving its palatability and flavor. This review summarizes the functional components of okara, their physiological functions, and the effects of microbial fermentation on their compositions and concentrations. The mechanisms by which these functional components exert beneficial effects, including regulation of gut microbiota composition, promotion of short-chain fatty acid production, enhancement of intestinal barrier function, and modulation of immune responses, are also discussed. The potential role of fermented okara in the prevention and management of obesity, diabetes, inflammatory bowel diseases, and other related disorders has also been explored. This review highlights the nutritional value of fermented okara, elucidates how its functional components interact with gut microbiota to promote host health, and provides a theoretical basis for the industrial development and application of fermented okara-based functional foods.