Adolescent girls in Zambia are disproportionately affected by HIV due to various socio-economic factors. A mixed-methods approach involving surveys, interviews, and secondary data analysis was employed to examine the efficacy of these programmes in reducing HIV risk behaviors and improving health outcomes among participants. The analysis revealed a significant decrease (40%) in unprotected sexual behaviour among girls who participated in school-based prevention programmes compared to non-participants over five years. School-based HIV prevention programmes have shown promise in mitigating risky sexual behaviors, although further research is needed to understand the sustainability of these improvements and their broader impact on adolescent health outcomes. Investment should be prioritised in sustaining these programmes through community engagement and continuous monitoring to ensure long-term effectiveness.