The aim of the present study was to examine the relationship between moral disengagement, emotion regulation and bullying behavior at school. Participants were 512 adolescents (281 males and 231 females) attending secondary schools in Cyprus. They completed a questionnaire package two times, with a five months period between them. Structural equation modeling (SEM) was applied to investigate the relationships among the variables under study. Moderation analyses were used to examine the moderating role of emotion regulation strategies on the effect of moral disengagement on bullying activity and multi-group analyses were further employed to examine the role of gender as a potential moderator. In line with earlier research, a positive association between moral disengagement and bullying behavior was found. Further, it was found that emotion regulation serves as a moderator of the effect of moral disengagement on bullying behavior. However, such moderation was found only for girls who use maladaptive emotion regulation strategies.