OBJECTIVE: This study assessed the role of governmental and non-governmental organizations in mitigation of stigma and discrimination among people infected and affected by HIV/AIDS in informal settlements of Kibera. METHODS: This was a descriptive cross-sectional study and used a multi stage stratified sampling method. The study was conducted in Kibera, an informal settlement with a population of over one million people which makes it the largest slum not only in Kenya but in sub-Saharan Africa. The study targeted infected individuals, non-infected community members, managers of the organizations implementing HIV/AIDS programmes and service providers. In the process 1331 households were interviewed using qualitative and quantitative data collection instruments. Statistical Package for Social Sciences (SPSS) and Nudist 4 packages were used to analyze the quantitative and qualitative data respectively. RESULTS: More than 61% of the respondents had patients in their households. Fifty five percent (55%) of the households received assistance from governmental and non-governmental organizations in taking care of the sick. Services provided included awareness, outreach, counseling, testing, treatment, advocacy, home based care, assistance to the orphans and legal issues. About 90% of the respondents perceived health education, counseling services and formation of post counseling support groups to combat stigma and discrimination to be helpful. CONCLUSION: Stigma and discrimination affects the rights of People Living with HIV/AIDS (PLWHAs). Such stigmatization and discrimination goes beyond and affects those who care for the PLWHAs, and remains the biggest impediment in the fight against HIV/AIDS in Kibera. Governmental and non-governmental organizations continue to provide key services in the mitigation of stigma and discrimination in Kibera. However, personal testimonies by PLWHAs showed that HIV positive persons still suffer from stigma and discrimination. Approximately 43% of the study population experienced stigma and discrimination.