Urban youth in Nairobi, Kenya face elevated rates of depression due to socio-economic challenges, educational pressures, and limited mental health resources. A mixed-method study using pre-post assessments, focus groups, and quantitative data analysis to evaluate CMHC impacts on youth depression levels. The proportion of depressed youths reduced by 25% post-intervention (95% CI: -18% to -34%) after enrolment in CMHCs, with thematic analyses revealing improved support-seeking behaviors and coping strategies. Community mental health centres significantly reduced urban youth depression rates, validating the need for such interventions in underserved urban areas. Expanding CMHC networks and integrating community resources are recommended to enhance mental health outcomes for disadvantaged youth. Urban Youth Depression, Community Mental Health Centres, Intervention Effectiveness Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.