Urban youth in Kampala slums face significant mental health challenges due to socioeconomic factors. A comprehensive search strategy was employed using databases such as PubMed and Web of Science. Studies were included if they reported longitudinal data from at least two years post-group formation. The review identified a significant reduction in depressive symptoms among participants (p < 0.05, effect size = -0.67), indicating the effectiveness of support groups in improving mental health outcomes. Urban youth mental health support groups show promise as an effective intervention strategy for reducing depression symptoms over time. Future research should focus on replicating these findings in diverse contexts and exploring longer-term impacts. Policy makers are encouraged to integrate such programmes into community health initiatives.