ObjectiveThis study aimed to examine the mediating role of Internet Addiction in the association between bullying victimization and Depressive Symptoms among left-behind children, as well as the moderating role of physical activity in this relationship.MethodsA cross-sectional design was adopted. A total of 21,689 left-behind children were recruited using stratified random sampling. A moderated mediation model was constructed within the generalized linear model framework. Conditional indirect ef