Glutathione transferase Omega 1 (GSTO1-1) is an atypical GST reported to play a pro-infammatory role in response to LPS. Here we show that genetic knockout of Gsto1 alters the response of mice to three distinct infammatory disease models. GSTO1-1 defciency ameliorates the inflammatory response stimulated by LPS and attenuates the infammatory impact of a high fat diet on glucose tolerance and insulin resistance. In contrast, GSTO1-1 defcient mice show a more severe inflammatory response and increased escape of bacteria from the colon into the lymphatic system in a dextran sodium sulfate mediated model of infammatory bowel disease. These responses are similar to those of TLR4 and MyD88 defcient mice in these models and confrm that GSTO1-1 is critical for a TLR4-like pro-infammatory response in vivo. In wild-type mice, we show that a small molecule inhibitor that covalently binds in the active site of GSTO1-1 can be used to ameliorate the infammatory response to LPS. Our fndings demonstrate the potential therapeutic utility of GSTO1-1 inhibitors in the modulation of infammation and suggest their possible application in the treatment of a range of inflammatory conditions.