This animal model study evaluated a self-cross-linked hydrogel delivery system combining cysteamine-grafted γ-polyglutamic acid with the tripeptide KPV in rats with TNBS-induced ulcerative colitis. The hydrogel formulation demonstrated improved stability of the KPV tripeptide and showed alleviating effects on colitis markers in the rat model. This represents preclinical research requiring further development before clinical translation.