Mucosal immune responses are rapid and offer both local and systemic immunological advantages, making them crucial for disease prevention. Ganoderma polysaccharides (GPs), which include β-(1→3) and β-(1→6) glycosidic bond configurations and triple-helix three-dimensional structures, possess immunoenhancing activities and hold significant potential as adjuvants, yet their application in mucosal immunity has been less reported. This study systematically reviewed the literature from the past 20 years using databases such as CNKI and PubMed, with key words including “Ganoderma polysaccharides”, “mucosal”, and “immunoadjuvant”. The composition of the mucosal immune system and the activation effects of GPs on antigen-presenting cells and lymphocytes were examined, clarifying the immunological effects and mechanisms of GPs as adjuvants across various mucosal sites, including the intestine, oral cavity, stomach, and nasal passages. Additionally, the potential applications of GPs in combination with nanotechnology were discussed. This review aims to provide a theoretical basis for further research and application of GPs in mucosal immunity.