Sofalcone (Sof), a synthetic analog of sophoradin, is a type of natural phenol derived from the traditional medicinal herb Sophora subprostrata, with potent anti-inflammatory activity. However, the mechanisms of action of Sof for treating intestinal-associated inflammation are not well known. In this work, we identified high mobility group box 1 (HMGB1) as the key covalent target of Sof for the anti-inflammatory activity in the human colonic epithelial cells through quantitative chemoproteomics profiling.