This study examined both the moderating effects of moral reasoning and gender on the relation between moral disengagement and cyberbullying in Chinese adolescents. Four hundred and seventeen adolescents completed the measures of Machiavellianism, moral disengagement, moral reasoning, and cyberbullying. The findings revealed that moral disengagement was significantly associated with cyberbullying even when Machiavellianism was controlled. Moral reasoning moderated the association between moral disengagement and cyberbullying. When adolescents reported a low level of moral reasoning, those with high moral disengagement reported higher scores in cyberbullying than those with low moral disengagement. However, the high and low moral disengagement group had a low level of cyberbullying when moral reasoning was high. Moreover, gender also moderated the link between moral disengagement and cyberbullying. Specifically, the relation between MD and cyberbullying tended to be stronger in boys than in girls. •Moral disengagement was significantly associated with cyberbullying even when Machiavellianism was controlled.•Moral reasoning moderated the association between moral disengagement and cyberbullying.•Gender also moderated the link between moral disengagement and cyberbullying.