Teachers respond differently to bullying and victimization. Socio-cognitive and moral domain theory suggest that students process teachers' behavior cognitively and that teachers' responses to incidents of bullying and victimization could affect students' level of moral disengagement. We examined the mediating effect of students' moral disengagement between types of teachers' responses to situations of bullying and victimization and individual bullying using multilevel mediation modelling. Participants were 609 students (50% boys, age M = 11.47, SD = 1.14) of central Italy, nested in 34 classes. Students rated the frequency of self-reported bullying and of teachers' responses to incidents of bullying and victimization on a 5-point Likert scale. Teachers' responses to bullying included non-intervention, mediation, group discussion, and sanctions. Teachers' responses to victimization included non-intervention, mediation, group discussion, and victim support. Results indicated that in the teachers' responses to incidents of bullying model, a significant indirect effect of non-intervention (β = .03; 95%CI [.01, .05]) and of sanctions (β = -.02; 95%CI [-.04, -.01]) on bullying through moral disengagement was found at the individual level. Similarly, in the model on teachers' responses toward victims there was a significant indirect effect through moral disengagement of non-intervention (β = .03; 95%CI [.02, .04]) and victim support (β = -.01; 95%CI [-.02, -.001]). At the class level there were no significant indirect effects. In sum, results indicated that moral disengagement is an important mediator at the individual level and suggest including teachers in anti-bullying interventions with a specific focus on their role for moral development.