Nairobi's informal settlements are hotspots of climate vulnerability, with poor drainage, heat traps, and limited access to healthcare. This study examines how climate stressors (heat, flooding, water scarcity) interact with poverty to intensify mental health issues such as depression, anxiety, and substance abuse. Data from Kibera and Mathare reveal that environmental stress compounds daily struggles of unemployment and insecurity, pushing vulnerable residents into harmful coping mechanisms. The paper underscores the need for integrated climate-mental health urban planning, community-based resilience hubs, and partnerships between psychologists, urban planners, and policymakers.