The purpose of this study is to investigate the mediating role of online and offline social sensitivity in the association between online vigilance and mental health outcomes—specifically depression, anxiety, and stress—among Algerian female university students. A cross-sectional study was conducted with 438 Algerian female university students. Validated scales were utilized to measure online vigilance, social sensitivity (both online and offline), and psychological distress. Data was analyzed using correlation and mediation analyses to explore the relationships among these variables and to assess the mediating effect of social sensitivity. The findings indicate a significant positive relationship between online vigilance, social sensitivity, and mental health problems. Online and offline social sensitivity fully mediated the influence of online vigilance on stress, anxiety, and depression. This suggests that higher engagement in online vigilance increases social sensitivity, which in turn heightens vulnerability to psychological distress. This study contributes to the understanding of the complex interplay between digital behaviors, social perceptions, and mental health among Algerian female university students. By highlighting the mediating role of social sensitivity, the research underscores the necessity for interventions that address online habits and enhance social coping skills to improve mental well-being in this population.