Background: Numerous studies have examined the two-way relationship between depression, bullying, and identity styles; But research that examines the relationship between depression and bullying and the mediating role of identity style has been neglected. Aims: The present study aimed to investigate the relationship between depression and bullying with the mediating role of identity in Secondary high school students. Method: This was a correlational study. The statistical population of the present study included all of tenth and eleventh grade students of Damghan city in the academic year of 2019-2020. 350 students were selected by random sampling. The present research instruments are: Per Eden (2000), the Illinois Bullying Standard Questionnaire (2001) and Brzonski's Identity Styles Questionnaire (1989). Data analysis was performed using correlation matrix. Results: The relationship between depression and bullying and victim variables was significant and positive, and the relationship between information identity style, normality and commitment with bullying and victim was negative, and the relationship between avoidant identity style with bullying and victim was positive (P< 0/001). It has also been shown that depression predicts both identity and indirect variables, bullying and victim variables, both directly and indirectly. Mediation also confirms the identity style in the relationship between depression and bullying. Conclusions: The relationship between depression and bullying in students is not a simple one, and this relationship is partly affected by the mediation of some important elements such as a person's identity style.