Introduction: While social networks have become an integral part of people's lives, they also bring the potential for negative consequences, with problematic social network use emerging as a noteworthy concern, especially among adolescents. Guided by social control theory, this study examined bidirectional relationships between problematic social network use and its influencing factors: school connectedness and social anxiety. Methods: Random intercept cross-lagged panel models were employed to examine the bidirectional relationships among school connectedness, social anxiety, and problematic social network use. Data were collected using the School Connectedness Scale, the Social Interaction Anxiety Scale, and the Evaluation Tool for Problematic Mobile Social Network Usage. Measurements were taken at three different times, each 6 months apart, over the course of 1 year (Time 1-3; T1 in November 2020). A total of 1684 Chinese adolescents (45.23% boys, M[subscript age] = 14.66, SD = 1.30) from a secondary school in Chaozhou City, Guangdong Province, China, participated in the study. Results: The results indicated school connectedness and problematic social network use negatively predicted each other over time. In contrast, a positive bidirectional relationship was found between social anxiety and problematic social network use. Conclusions: The findings have important implications for the development of targeted intervention strategies aimed at promoting healthy online habits and preventing the escalation of problematic social network use among adolescents. By highlighting the dynamic interplay between school connectedness, social anxiety, and social network use, this study contributes to a deeper understanding of these issues and lays the groundwork for future research and interventions aimed at supporting adolescents in navigating the digital landscape.