This study examines the impact of school-wide mental health interventions on adolescent self-esteem and academic performance in Kampala secondary schools in Uganda. A comparative study design was employed, utilising pre- and post-intervention surveys administered to a representative sample of students across participating schools. Data analysis included statistical tests for significance and comparisons between intervention groups and controls. The findings indicate a modest but statistically significant improvement in self-esteem scores among adolescents who received the mental health interventions compared to those without such support, with an average increase of 10% in self-reported confidence levels. School-wide mental health programmes appear effective in enhancing adolescent self-esteem and potentially improving academic performance. However, further longitudinal studies are needed to confirm these initial results and explore other potential benefits. Educational authorities should consider implementing comprehensive mental health support systems within schools as a means of promoting overall student well-being and educational outcomes.