Extracellular polysaccharide (EPS) refers to multifaceted biopolymers synthesized by microorganisms, primarily composed of polysaccharides, along with smaller proportions of proteins, nucleic acids, lipids, and humic substances. Negatively charged bioactive EPS (10–1000 kDa) tend to play an important role in regulating immune response. They enhance both innate and acquired immunity, with their effects being dependent on their molecular characteristics, such as size, structure, molecular weight, functional groups, monosaccharide composition, and charge. EPS stimulates macrophages through a canonical signaling pathway that involves the activation of NF-κB via the degradation of IκBα. It may also promote production of cytokines (TNF-α, IL-6, and IL-10). Moreover, this polysaccharide aid in activating T and B cells and thereby strengthens the overall effectiveness of the immune system. Additionally, EPS can enhance resistance against various pathogens, emphasizing their significance in immune defense. The incorporation of extracellular polysaccharides into functional foods has the potential to significantly enhance host health by harnessing their immunomodulatory properties. Fermented dairy products such as yogurt or kefir fortified with specific microbial strains exhibit the potential of EPS to improve gut health and strengthen immune functions. Furthermore, these products not only enhance digestive health but also provide protective benefits against viral infections, making them valuable components of a health-focused diet. Clinical investigations have revealed the anticancerous, antimicrobial, and immunomodulatory properties of EPS. Extracellular polysaccharides derived from specific bacterial strains have shown significant promise in enhancing immune function and mitigating symptoms associated with inflammatory bowel disease. These findings highlight the vast therapeutic potentials of these biopolymers in the development of functional foods tailored to support immune health.