HIV/AIDS remains a significant public health concern in Nigeria, particularly among adolescents where sexual activity patterns can influence transmission rates. The study employed a qualitative research design involving semi-structured interviews with participants aged 15-18 years who had participated in at least one HIV/AIDS prevention programme. Data collection was conducted through thematic analysis of interview transcripts, focusing on contextual factors that affect sexual behaviour and preventive measures adoption. Among the interviewed teenagers, there was a notable reduction in reported unprotected sex post-programme participation, with about half adopting consistent condom use as recommended by health educators. The findings suggest that structured HIV/AIDS prevention programmes can positively influence teenagers' sexual behaviors and adherence to preventive measures. However, sustained support is necessary for long-term behaviour change. Health education curricula should be reinforced with community-based interventions targeting families and schools to ensure comprehensive sexual health education and support systems are in place.