Necrotizing enterocolitis (NEC) stands as the most prevalent and severe gastrointestinal ailment affecting premature newborns, particularly those with extremely low birth weights. Intestinal barrier dysfunction emerges as a crucial factor in NEC's pathogenesis. REGγ predominantly manifests in the intestinal epithelium and has shown to regulate experimental colitis. However, the potential correlation between REGγ and NEC remains ambiguous. This study reveals that REGγ is notably overexpressed in both human and murine NEC samples. REGγ-deficient mice displayed improvements in intestinal mucosal inflammation and reduced NEC severity. Additionally, REGγ deficiency notably lowered the expression of phosphorylated transcription factor p65 and inflammatory factors in intestinal epithelial cells of NEC-afflicted mice. REGγ exacerbates the local inflammation by triggering the degradation of IκBɛ, a negative regulator of NFκB. Clinically, REGγ and p65 expression levels exhibit a positive correlation in NEC specimens. Moreover, pre-treatment of mice with a p65 inhibitor effectively suppressed the expression of inflammatory mediators and alleviated REGγ-mediated NEC development. These findings underscore that abnormal upregulation of REGγ triggers NEC development by enhancing NF-κB activity and exacerbating epithelial barrier dysfunction. Thus, novel therapeutic approaches targeting REGγ inhibition may offer enhanced treatment for NEC.