Purpose The aim of this study was to examine the effect of adolescents' exposure to media portraying antisocial and risk behavior on cyberbullying behavior over time. Previous research established relatively high prevalence of cyberbullying behavior among adolescents, although not much is known about the possible predictors of cyberbullying behavior. This study examines the long-term effects of media exposure herein. Furthermore, we examined whether boys and girls differ in this respect. Methods The long-term effects were tested in a longitudinal design with three waves (N = 1,005; age range, 11-17 years; 49% boys). Measured variables: cyberbullying behavior and exposure to media with antisocial and risk behavior content. Results Results of mixed-model analyses showed that higher levels of exposure to media with antisocial and risk behavior content significantly contributed to higher initial rates of cyberbullying behavior. Moreover, an increase in exposure to antisocial media content was significantly related to an increase in cyberbullying behavior over time. For both boys and girls, higher exposure to antisocial and risk behavior media content increases cyberbullying behavior over time though more clearly for boys than for girls. Conclusions This study provided empirical support for the amplifying effect of exposure to antisocial media content on adolescents' cyberbullying behavior over time. Results are discussed in view of adolescents' media use and the larger theoretical framework.