Using an ecological perspective, this one-year longitudinal study examined the moderating effect of sex in the associations among peer-related contexts (i.e., peer attachment, social preference goals) and cyberbullying involvement among adolescents from China, Cyprus, India, and the United States, along with investigating cross-cultural differences in these associations. Participants were 2,452 seventh and eighth grade adolescents (age range 12–16 years old; 49.1% girls) from China, Cyprus, India, and the USA. Adolescents completed questionnaires on peer attachment, social preference goals, and cyberbullying involvement (i.e., perpetration, victimization) at Time 1. Cyberbullying involvement was administered at Time 2 (one year later). Peer attachment and social preference goals were negative predictors of Time 2 cyberbullying involvement. Peer attachment and Time 2 cyberbullying perpetration were moderated by sex for Chinese adolescents only, as well as social preference goals and Time 2 cyberbullying perpetration for Chinese and the US adolescents. Sex did not moderate the associations among peer attachment, social preference goals, and Time 2 cyberbullying victimization. The findings of this study have implications for interventions focused on improving adolescents’ interactions with their peers at school and urges the need to develop bullying prevention programs sensitive to culture and sex. The ecological framework contributes to a more complete understanding of how multiple contexts influence bullying dynamics and provides a clear basis for policy and intervention.