Adolescents’ experiences of bullying victimization are positively associated with their post-traumatic stress symptoms. The development of these symptoms alongside experiences of bullying victimization over time, however, are not well understood. The current study used a transactional theory of development to examine the bidirectional associations between adolescents’ post-traumatic stress symptoms and experiences of cyber and traditional victimization across three academic years. Participants were 510 Canadian students in grade 7 or 10 (Mage = 13.7, 61.6% girls) who completed surveys annually. The findings show that adolescents’ concurrent experiences of cyber and traditional victimization were uniquely associated with their post-traumatic stress symptoms. Over time, greater post-traumatic stress symptoms were associated with more experiences of cyber and traditional victimization among adolescent boys and girls. Prevention and intervention efforts must address the role of post-traumatic stress symptoms that may limit adolescents’ ability to develop or maintain healthy relationships.