The present study investigated how teachers' cyberbullying experiences are associated with their mental health. Data of 372 school teachers in Germany were assessed via online surveys. Overall, 91.1% of the teachers reported that cyberbullying is an issue at their school, and 69.9% wanted more training in how to manage cyberbullying. In a moderated mediation analysis, the positive association between cyberbullying experience and stress symptoms was mediated negatively by positive mental health (PMH), i.e., the higher the cyberbullying experience, the lower the PMH and the higher the stress symptoms. Teachers' cybercompetence in managing cyberbullying moderated the link between PMH and stress symptoms. Specifically, the higher the cybercompetence, the weaker their association. Therefore, among persons with high cybercompetence the decrease of PMH caused by cyberbullying experience could contribute to a lesser increase in stress symptoms. Teachers' training in managing cyberbullying is discussed as an approach to protect teachers' and students' mental health.