Postbiotics, non-living microbial components and metabolites, are gaining attention as potential biotherapeutics for various diseases, including metabolic disorders. This review highlights their role in modulating the gut microbiota, immune system, and metabolic pathways. Postbiotics, derived from microorganisms, can provide health benefits without the need for live bacteria, making them safer for vulnerable populations. They include components like cell wall fragments, short-chain fatty acids (SCFAs), exopolysaccharides, and bacteriocins. Postbiotics can modulate the intestinal microbiota, improve epithelial barrier function, regulate immune responses, and influence systemic metabolic processes. SCFAs, such as acetate, propionate, and butyrate, are particularly important for metabolic health, influencing glucose, lipid, and energy metabolism. Postbiotics have shown potential in improving gut health, reducing inflammation, and preventing metabolic diseases. In children, postbiotics like fermented infant formulas and specific microbial components have been shown to enhance immune function, reduce inflammation, and improve gut microbiota composition. In adults with metabolic disorders, postbiotics such as SCFAs and cell wall components have demonstrated anti-inflammatory, anti-obesogenic, and cardiometabolic benefits. Postbiotics also show promise in neurological and immune-related conditions, such as depression and multiple sclerosis. The mechanisms of action include modulation of the microbiota, immune responses, and metabolic pathways. Future research is needed to fully understand their therapeutic potential and to develop effective postbiotic formulations for clinical use.Postbiotics, non-living microbial components and metabolites, are gaining attention as potential biotherapeutics for various diseases, including metabolic disorders. This review highlights their role in modulating the gut microbiota, immune system, and metabolic pathways. Postbiotics, derived from microorganisms, can provide health benefits without the need for live bacteria, making them safer for vulnerable populations. They include components like cell wall fragments, short-chain fatty acids (SCFAs), exopolysaccharides, and bacteriocins. Postbiotics can modulate the intestinal microbiota, improve epithelial barrier function, regulate immune responses, and influence systemic metabolic processes. SCFAs, such as acetate, propionate, and butyrate, are particularly important for metabolic health, influencing glucose, lipid, and energy metabolism. Postbiotics have shown potential in improving gut health, reducing inflammation, and preventing metabolic diseases. In children, postbiotics like fermented infant formulas and specific microbial components have been shown to enhance immune function, reduce inflammation, and improve gut microbiota composition. In adults with metabolic disorders, postbiotics such as SCFAs and cell wall components have demonstrated anti-inflammatory, anti-obesogenic, and cardiometabolic benefits. Postbiotics also show promise in neurological and immune-related conditions, such as depression and multiple sclerosis. The mechanisms of action include modulation of the microbiota, immune responses, and metabolic pathways. Future research is needed to fully understand their therapeutic potential and to develop effective postbiotic formulations for clinical use.