Community-led mental health campaigns have emerged as a promising approach to address stigma and improve access to care in underserved communities such as Kibera, Nairobi, Kenya. A mixed-methods approach was employed, including pre-and post-campaign surveys, focus group discussions, and participant observation. Data were analysed using descriptive statistics and thematic analysis. In the first year of the campaign, adherence rates to recommended mental health activities increased by 25% compared to baseline levels (p < .01), with themes emerging around community engagement and service uptake. The findings suggest that sustained community-led initiatives can enhance mental health service utilization in a marginalized urban setting. Long-term sustainability strategies, including financial support and capacity-building for local leaders, are recommended to ensure the continuation of these programmes. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.