School-based HIV/AIDS prevention programmes are critical in mitigating the spread of HIV among adolescents in Nairobi District schools in Kenya. A mixed-methods design was employed, integrating quantitative data from standardised test scores with qualitative insights from student interviews and teacher observations. Statistical analysis utilised logistic regression models to assess programme efficacy. The preliminary findings suggest that students who participated in the school-based programmes showed a statistically significant improvement (OR = 1.5, p < 0.05) in their academic performance compared to non-participants. While the results indicate potential positive impacts on student learning outcomes, further longitudinal studies are recommended to confirm these effects and explore broader contextual factors influencing programme success. Educational authorities should prioritise integrating technology into HIV/AIDS prevention curricula and consider implementing regular follow-up assessments to track long-term impact.