Urban Senegalese adolescents face significant mental health challenges, necessitating innovative solutions. A mixed-methods approach was employed, including quantitative survey data collection and qualitative interviews with participants. The study utilised cross-sectional designs for both phases of the research. Mobile health apps were used by 45% of surveyed adolescents, predominantly for mood tracking (70%) and stress management (62%). The mixed-methods study provided insights into the acceptance and use of mobile health applications in this demographic, identifying key areas for future research. Future studies should focus on enhancing app functionality to better support adolescents' mental health needs and explore the long-term effects of these interventions. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.