This review article discusses the structural features, biological activities, and production strategies of yeast cell wall mannan. Yeast cell wall mannan is a major component of the cell wall, accounting for 30–50% of the cell wall mass. It is composed of mannose residues linked to proteins and is involved in various biological functions, including immune regulation, gut health, and antioxidant activity. The cell wall of yeast contains various polysaccharides, including β-glucan, chitin, and mannan, which have different structural and functional properties. Mannan is a key component of the yeast cell wall and has been studied for its potential applications in food, feed, and pharmaceutical industries. The review highlights the importance of mannan in promoting gut health, enhancing immune responses, and exhibiting antioxidant properties. It also discusses the methods for mannan production, including yeast strain engineering and metabolic engineering approaches to enhance mannan accumulation in the cell wall. The review emphasizes the potential of yeast cell wall mannan as a valuable resource for industrial applications and further research.This review article discusses the structural features, biological activities, and production strategies of yeast cell wall mannan. Yeast cell wall mannan is a major component of the cell wall, accounting for 30–50% of the cell wall mass. It is composed of mannose residues linked to proteins and is involved in various biological functions, including immune regulation, gut health, and antioxidant activity. The cell wall of yeast contains various polysaccharides, including β-glucan, chitin, and mannan, which have different structural and functional properties. Mannan is a key component of the yeast cell wall and has been studied for its potential applications in food, feed, and pharmaceutical industries. The review highlights the importance of mannan in promoting gut health, enhancing immune responses, and exhibiting antioxidant properties. It also discusses the methods for mannan production, including yeast strain engineering and metabolic engineering approaches to enhance mannan accumulation in the cell wall. The review emphasizes the potential of yeast cell wall mannan as a valuable resource for industrial applications and further research.