This research examined the relationship of character strengths with peer bullying and peer victimization. The research group consists of 663 high school students in Kocaeli chosen by convenience sampling method. Character Growth Index, Peer Bullying Scale Adolescent Form and Personal Information Form have been used. The results indicated that peer bullying was related to the strengths of perseverance, humility, optimism, kindness, love/care, calmness, wisdom, spirituality, and honesty, while no relationship was found with courage and forgiveness. It was also found that peer victimization was related to the strengths of perseverance, humility, optimism, kindness, love/care, calmness, courage, wisdom, spirituality, and honesty character strengths, while there was no correlation with the strength of forgiveness. As a result of the regression analysis, the strength of perseverance and honesty in the Character Growth Index explained 10% of the total variance in being a victim of peer bullying, while the strength of perseverance, humility, spirituality, and honesty in the Character Growth Index explained 16% of the total variance in performing peer bullying. In the examination made according to the gender variable, it was found that there was a statistically significant difference in the sub-dimensions of optimism, kindness, calmness, courage, wisdom, and honesty in the Character Growth Index scale according to gender. Again, according to the gender variable, it was found that the total peer victimization and total peer bullying scores of the students were higher in male students than in female students.