Inflammatory bowel diseases (IBD) are chronic, relapsing gastrointestinal disorders with complex pathological mechanisms and limited treatment options, caused by various uncertain factors. Zinc plays a crucial role in wound healing, tissue regeneration, and immune responses. While zinc deficiency is common among patients with IBD, the effects of dietary zinc supplementation on the disease course remain unclear. In this study, 125 male C57BL/6 J mice were randomly divided into five groups: a control group (Con), a 2,4,6-trinitrobenzenesulfonic acid (TNBS) induction group, and three zinc supplementation groups receiving 160 ppm, 400 ppm, and 1000 ppm of zinc oxide nanoparticles ( ZnO NPs), respectively. The results showed that dietary supplementation with ZnO NPs significantly alleviated damage to the colonic mucosal epithelial cells and crypts in IBD mice, while effectively reducing the inflammatory response. Furthermore, ZnO NPs helps maintain the quantity and secretion function of goblet cells, restores normal expression levels of tight junction proteins (ZO-1, occludin), and proliferating cell nuclear antigen (PCNA), and preserves the diversity of gut microbiota. Notably, a significant protective effect was observed with dietary zinc supplementation at 160 ppm. These findings suggest that ZnO NPs significantly improves TNBS-induced intestinal inflammatory damage by modulating the gut microbiota, mucus, and mechanical barriers.