This study investigated the emulsifying properties of a hot water extracted polysaccharide (SCMP) derived from liquid fermentation mycelium of Schizophyllum commune in stabilizing oil-in-water (o/w) emulsions. SCMP demonstrated the ability to stabilize o/w emulsions (referred to as SCMPe) for extended periods (>21 days) even at low concentrations (2 g/L) and increased the viscosity and elasticity of the emulsion system. Through confocal laser-scanning microscope visualization, it was observed that SCMP created a physical barrier on the surface of the oil droplets, contributing to emulsion stability. Furthermore, SCMPe demonstrated excellent tolerance to varying concentrations of Na+ (0.1–0.5 mol/L) and Ca2+ (0.01–0.05 mol/L) as well as a wide pH range (3.0–9.0). Moreover, increasing SCMP concentration effectively inhibited lipid oxidation and improved the stability of β-carotene and curcumin in the emulsion during storage. A detailed analysis of SCMP's composition and structure was done to better understand its emulsifier properties, revealing SCMP to be composed of two β-glucans with a rigid chain and high molecular weight. These results suggest that SCMP holds great potential an efficient stabilizer in the food industry, particularly in enhancing emulsion stability.