A polysaccharide named Senegrain Water-Soluble Polysaccharide (SWSP) was extracted and purified from Senegrain seeds. The physicochemical properties of SWSP were evaluated by Thin-layer chromatography (TLC), High Performance Liquid Chromatography (HPLC), Scanning Electron Microscopy (SEM), and Differential Scanning Colorimeter (DSC). TLC results showed that SWSP is a gluconic acid polymer. It had a network with a large number of cavities. This polysaccharide with a semi-crystalline structure has an average molecular weight of 47.42 kDa. On other trend, obtained data exhibited potent antidiabetic and antibacterial activities of SWSP. Additionally, the antioxidant activities of SWSP were studied in vitro, and demonstrated that this polymer displayed an interesting ABTS radical scavenging activity as well as a protective effect on the hydroxyl radical-induced DNA damage. The effects of SWSP on oxidative processes in minced raw beef during refrigerated (4 °C) storage were investigated. The results proved that SWSP decreased the TBARS value and inhibited the MetMb accumulation during the period of refrigeration storage. Overall, the finding demonstrated the potential applications of SWSP in food industries.