Adolescence is a critical developmental period characterized by profound physical, emotional, cognitive, and social changes. While most adolescents navigate these transitions successfully, many experience mental health challenges that can significantly impact their well-being, educational achievement, relationships, and future life outcomes. Mental disorders such as depression, anxiety, substance use disorders, eating disorders, self-harm behaviors, and suicide have become increasingly prevalent among adolescents worldwide. Multiple biological, psychological, familial, social, and environmental factors contribute to mental health vulnerabilities during this period. This review explores the epidemiology, major mental health challenges, risk factors, consequences, assessment approaches, prevention strategies, and emerging interventions aimed at promoting adolescent mental well-being. Strengthening mental health services, school-based programs, family support systems, and digital health solutions are essential for addressing the growing burden of adolescent mental health disorders.