Ulcerative colitis (UC) is an autoimmune disease afflicting an increasing number of patients and increasing demands towards the development of efficacious and safe drugs. Recently, with increasing interest in alternative medicines, natural resources have become a hotspot for drug discovery against UC. In addition to being consumed as a food and spice, ginger is also widely used as a well-recognized gastrointestinal herbal medicine. With a long history in the treatment of digestive disorders, the potential of ginger in alleviating UC has been documented in several experimental models and clinical trials. However, as a major active constituent of ginger, ginger polysaccharides (GP) and its effect on UC has yet to be reported. In this study, GP was firstly separated and characterized. In a dextran sulfate sodium (DSS)-induced colitis mouse model, GP alleviated UC symptoms by inhibiting pro-inflammatory cytokines levels to regulate intestinal inflammation, repairing the intestinal barrier as indicated by occludin-1 and ZO-1, as well as regulating gut microbiota. Taking these results together, we believe GP could be an innovative option in developing functional foods or therapeutic agents for UC management.