The goal of this study was to investigate the moderating effect of parental mediation in the longitudinal associations among cyberbullying bystanding, depression, subjective health complaints, and self-harm. Participants were 1,067 seventh and eighth graders (M age = 13.93; 50% female) from the suburbs of a large Midwestern city in the United States. Restrictive parental mediation and instructive parental mediation strategies moderated the relationships examined in this study. Increases in restrictive parental mediation strengthened the association between cyberbullying bystanding and depression, subjective health complaints, and self-harm. High instructive parental mediation weakened these associations. These findings underscore the importance of developing interventions that increase parents' awareness of how to implement effective parental mediation strategies. Parental intervention programs that focus on parents' role in mitigating their children's exposure to cyberbullying and how they can help reduce the associated negative outcomes should be developed.