It is estimated that, globally, the mean point prevalence of diagnosable mental disorders in children and adolescents is higher than 11%, and around half of cases of major mental disorders have their onset before the age of 18. Mental disorders with onset in childhood or adolescence have an enormous impact on the developing brain, body and personal identity, as well as on the short- and long-term social, educational and functional capacity of individuals. Child and adolescent psychiatry – as a discipline, profession, academic field, and network of clinical services – is still relatively young, with its formal evolution beginning in the 20th century. Therefore, it is not surprising that there are currently many challenges, but also opportunities and expected future developments, in this area. In this paper, we identify and address the core challenges, possible solutions, opportunities, and future directions of child and adolescent psychiatry. In the first part of the paper, challenges and possible solutions are discussed regarding diagnostic issues, stigma, access to care, shortage of mental health professionals, evidence-based treatments, treatment adherence, parental participation/engagement, integration with schools, digital influences and cyberbullying, and war/forced displacement. In the second part, opportunities and developments are addressed that relate to early identification and intervention, resilience, interdisciplinary collaborations, integration with primary care, community-based approaches, use of digital technologies, precision child and adolescent psychiatry, artificial intelligence and related ethical issues, and cultural diversity and competences. Despite the significance and impact of mental disorders in children and adolescents, clinical delivery and research on these conditions remain underfunded and underprioritized, even in high-income countries, with clinical services and prevention/early intervention research receiving minimal investment. Addressing mental health in children and young people requires multi-level strategies beyond individual treatment, including tackling structural and socioeconomic barriers and creating opportunities for strengthening resilience and well-being. A well-trained workforce, adequate policies, and increased public awareness are crucial. Overall, the current gaps demand urgent action and global funding rebalancing to more adequately meet the critical needs of children and young people challenged by mental illness.