Lagos, Nigeria's largest city, houses numerous informal settlements where youth mental health services are often inaccessible and underutilized. A comparative study was conducted using qualitative interviews with service users and quantitative data on app usage patterns among youth in four selected settlements. The mobile app significantly increased awareness (72%) and use of mental health resources by the target population, though uptake varied across different socio-economic backgrounds. The mobile app effectively served as a tool to bridge service gaps but requires tailored adaptations for diverse user needs. Tailored interventions are recommended based on findings from this study to enhance the usability and impact of such apps in underserved areas. Mobile Apps, Youth Mental Health Services, Accessibility, Informal Settlements, Lagos