The relationship between probiotics and immune function has garnered significant scientific interest due to the crucial role of gut microbiota in modulating immune responses and enhancing host defense mechanisms. This research delves into the complex interactions between probiotics and the immune system, focusing on how specific strains of beneficial bacteria influence the composition and activity of gut microbiota. By examining both preclinical and clinical studies, this review elucidates the mechanisms through which probiotics contribute to immune regulation, including the modulation of cytokine production, enhancement of mucosal barrier function, and the promotion of immune cell differentiation and activity. Furthermore, the potential therapeutic applications of probiotics in managing immune-related disorders, such as allergies, autoimmune diseases, and infections, are explored. This comprehensive analysis underscores the promise of probiotics as a natural strategy to bolster immune health, providing a foundation for future research and clinical applications.