Community-based HIV/AIDS prevention interventions have been implemented in Kibera slums of Nairobi to address stigma and promote behavioural changes among residents. A mixed methods approach was employed, integrating both qualitative interviews and quantitative surveys to comprehensively assess the impact of the interventions over two years. Qualitative data revealed themes such as improved communication between healthcare providers and patients regarding HIV/AIDS. Quantitatively, there was a significant reduction in stigma scores among participants (p < 0.05), indicating behavioural changes towards more open attitudes towards HIV-positive individuals. The mixed methods study demonstrated that community-based interventions can effectively reduce stigma and foster positive behavioural change related to HIV/AIDS within Kibera slums, offering insights for future public health strategies in urban African settings. Future research should focus on replicating these findings across different communities in Nairobi and exploring the long-term sustainability of such interventions. HIV/AIDS, stigma reduction, behavioural change, community-based interventions, Kibera slums, mixed methods study