School-based health education programmes have been implemented in West African countries to address adolescent girls' health needs, but their effectiveness varies. A mixed-methods approach combining quantitative surveys (n=500) with qualitative interviews (n=30). Data were analysed using SPSS version 26.0 for descriptive statistics and inferential tests including ANOVA with robust standard errors. Significant increases in knowledge scores (p<0.01; mean difference = +5.2%) across all three countries, indicating improved health education outcomes. The programmes showed positive impacts on adolescent girls' health literacy and behaviors, though variability exists between countries. Further studies should explore long-term effects and sustainability of these interventions. adolescent girls, school-based health education, West Africa, Nigeria, Ghana, Senegal