The Kibera slum in Nairobi is a densely populated area with high prevalence of HIV among sex workers. A mixed-methods approach combining qualitative interviews and quantitative surveys was employed to gather data from 200 sex workers. Data were analysed using thematic analysis for qualitative insights and descriptive statistics for quantitative results. Among the surveyed participants, 45% reported engaging in unprotected sexual activities due to lack of access to condoms, while 38% cited financial constraints as a significant barrier to preventive measures. The study highlights the complex interplay between socio-economic factors and HIV transmission among sex workers. Recommendations include expanding condom availability and improving economic support for vulnerable populations. Implementing targeted interventions such as community-based health education programmes and microfinance schemes can significantly reduce HIV transmission rates in Kibera slum.