Background: Social media has become an integral part of daily life for adolescents but it is influencing their mental well being significantly. This study investigates social media usage patterns among students of a Government Senior Secondary School in Abuja and their effects on mental health. Methods: A cross-sectional study was conducted with a sample of 265 students, selected through systematic random sampling. Data were collected on age, gender, family structure, social media use, experiences of cyberbullying, and mental health indicators via a structured self-administered questionnaire. Analysis utilized IBM-SPSS version 27, employing descriptive statistics for quantitative variables and Chi-square tests for categorical variables (p ≤ 0.05). Results: Findings revealed that 56.9% of respondents were aged 16-18 years, with 60% female. Most (58.5%) used social media for 1-3 hours daily, while 6.9% exceeded 10 hours. Motivations included social connection and entertainment, with 17.3% reporting experiences of cyberbullying. Mental health assessments indicated that 56.5% displayed poor mental health, though 42.3% retained optimism. Notably, family structure significantly affected digital engagement (p = 0.001). Conclusion: This study underscores the prevalent use of social media among adolescents and its substantial impact on mental health, highlighting factors like cyberbullying. The alarming rate of poor mental health emphasizes the need for targeted interventions, including digital literacy education, enhanced mental health support, and community programs to promote responsible social media use.