Background <p>Adolescence is a critical developmental stage in which social interaction needs and digital engagement are heightened, making social media addiction a growing concern for mental health.</p> Methods <p>This study aimed to investigate the direct relationship between social media addiction and adolescents’ emotional and psychological well-being, as well as the mediating roles of cyberbullying and cyber victimization. A cross-sectional design was employed, and data were analyzed using correlation and mediation analyses (PROCESS macro, Model 6) to test the direct and indirect effects among the study variables. Data were collected from 1,626 middle school students in Türkiye during the 2024–2025 academic year using scales that measure social media addiction, well-being, and cyberbullying experiences.</p> Results <p>Correlation analyses indicated that social media addiction was negatively associated with emotional and psychological well-being and positively associated with both cyber victimization and cyberbullying. Mediation analyses further revealed that cyber victimization and cyberbullying acted as significant independent and sequential mediators of this relationship.</p> Conclusions <p>These findings demonstrate that excessive social media use not only directly reduces well-being but also contributes to harmful online interactions that exacerbate the adverse effects. These results underscore the necessity of comprehensive prevention and intervention strategies that jointly address social media addiction, cyberbullying, and cyber victimization. School-based programs developed in collaboration with nurses, educators, and mental health professionals can foster digital literacy, emotional regulation, and social competence, contributing to safer digital environments and improved psychological well-being among adolescents.</p>