Community workshops have been implemented to address HIV/AIDS prevention among female sex workers (FSWs) in Nairobi's slums. These initiatives aim to provide education and support services, but their impact is often under-researched. A mixed-method approach was employed, including quantitative analysis through a feedback survey and qualitative interviews for deeper insights. A convenience sampling method was used to select participants from FSW groups who attended workshops in Nairobi's slums Data were analysed using descriptive statistics and thematic content analysis. A proportion of 78% reported an increase in knowledge about HIV/AIDS transmission, with a significant improvement noted (p < 0.01) in the mean score on workshop-related questions compared to baseline surveys conducted before workshops. The feedback survey methodology revealed promising improvements in FSWs' knowledge and attitudes towards HIV/AIDS prevention post-workshop, suggesting effective engagement strategies can be developed based on these findings. Future research should explore the long-term effects of community workshops and consider implementing additional support services to enhance sustainability. Policy makers could also benefit from this study by identifying key areas for intervention in FSW communities. HIV/AIDS prevention, female sex workers, Nairobi slums, feedback surveys, impact analysis Model estimation used $\hat{\theta}=argmin_{\theta}\sum_i\ell(y_i,f_\theta(x_i))+\lambda\lVert\theta\rVert_2^2$, with performance evaluated using out-of-sample error.