Adolescent sexual abuse is a significant public health issue in Kenya, affecting behaviors and attitudes crucial for societal development. A mixed-methods approach combining pre- and post-intervention surveys with qualitative interviews among adolescents in selected schools across Kenya. Post-intervention, a statistically significant reduction ($p < 0.05$) was observed in adolescent perceptions of sexually abusive behaviour (72% vs. 60%) compared to baseline studies. School-based sexual abuse intervention programmes have a positive impact on adolescents' attitudes towards sexual abuse prevention. Expand programme implementation and integrate community engagement for sustained behavioural change.