The hemidesmosome, critical for epithelial cell adhesion to the basement membrane, relies on integrin beta 4 (itgb4) as a central component. Mutations of Itgb4 caused intestinal epithelial cell exfoliation in mammals, highlighting its essential role in maintaining epithelial integrity. However, the distribution and function of itgb4 in fish intestines remain poorly understood. Fish intestines, unlike those of terrestrial animals, are constantly exposed to environmental pathogens such as Vibrio anguillarum, Edwardsiella piscicida, and Aeromonas salmonicida, which can cause significant intestinal epithelial cell exfoliation and compromise mucosal barrier function. Investigating the role of itgb4 in this context is crucial for developing strategies to prevent intestinal pathogen infections in aquaculture. This study analyzed the distribution, function, and expression of itgb4 during pathogenic infection in the intestines of Scophthalmus maximus (turbot). Results revealed that Itgb4 protein is predominantly localized in intestinal epithelial cells, particularly at the cell membrane, and its expression significantly decreased during early stages of pathogenic bacterial infection. Interfering with itgb4 led to severe exfoliation of intestinal epithelial cells, accompanied by the downregulation of adhesion-related proteins and upregulation of immune-related genes. In turbot intestinal cells, itgb4 interference increased cell migration, underscoring its critical role in maintaining stable cell adhesion. Furthermore, itgb4 knockdown in zebrafish weakened intestinal epithelial cell adhesion and altered skin epithelial morphology, demonstrating its broader role in epithelial integrity. Importantly, we identified miR-483 as a key regulator of itgb4 during pathogenic infection. miR-483 exhibited an expression pattern opposite to that of itgb4. Both in vitro and in vivo experiments confirmed its role in regulating intestinal epithelial cell exfoliation by targeting itgb4. This study reveals the critical role of itgb4 in maintaining fish intestinal epithelial adhesion and its regulation by miR-483, offering new insights for improving mucosal barrier function and disease resistance in aquaculture. These findings highlight itgb4 as a potential therapeutic target to enhance disease resistance in economically important fish species.