BACKGROUND: Inflammatory bowel disease (IBD) is a chronic inflammatory bowel disease with no clinical cure. Excessive production of reactive oxygen species (ROS) at the inflammatory sites leads to the onset and progression of IBD. And the current non-invasive imaging methods are not ideal for the diagnosis and monitoring of IBD. METHODS: Herein, we developed inulin (IN)-coated cerium oxide nanoparticles (CeO(2)@IN NPs) for treatment and monitoring of IBD guided by computed tomography (CT). The physicochemical properties, ROS scavenging ability and CT imaging capabilities of CeO(2)@IN were investigated in vitro. Moreover, the therapeutic and targeted inflammation imaging effects of CeO(2)@IN were validated in dextran sulfate sodium (DSS)-induced colitis model. RESULTS: CeO(2)@IN with catalase (CAT) and superoxide dismutase (SOD) capabilities effectively scavenged ROS, thus protecting the cells against oxidative stress. In colitis model mice, orally administered CeO(2)@IN successfully traversed the gastrointestinal tract to reach the colon under the protection of IN, and effectively reduced intestinal inflammation, thereby maintaining the intestinal epithelial integrity. Notably, CeO(2)@IN performed better than conventional CT contrast agents for gastrointestinal tract imaging, particularly in detecting the inflamed areas in the colon. In addition, CeO(2)@IN exhibited excellent biocompatibility in vitro and in vivo. CONCLUSION: The study provided a novel integrated diagnostic and therapeutic tool for the treatment and monitoring of IBD, presenting great potential as a clinical application for IBD.