Digital mental health (DMH) interventions leveraging digital technologies, such as mobile applications, web-based platforms, artificial intelligence and wearable devices, have emerged as a promising avenue for addressing the mental health needs of young people. This scoping review examines the landscape of primary and secondary preventive DMH interventions for young people aged 10-24 years. Six electronic databases were searched, leading to a final incorporation of 81 studies published between 2010 and 2022. Each of these studies corresponds to a unique DMH intervention. Our findings reveal that research activity in the area of promotive and preventive DMH interventions started gaining ground from 2019 onwards, with the majority of studies conducted in Australia and the USA. 70% of the total studies targeted the prevention of mental health conditions. Randomized controlled trials were the predominant study methodology, while mental well-being, depressive disorders, anxiety disorders, life skills and disorders specifically associated with stress were the most targeted mental health or well-being conditions. Finally, mobile applications and web interfaces were the most studied form of DMH interventions. Most of these applications have integrated advanced AI/ML algorithms to serve the purpose of personalization and real-time monitoring. However, there is a marked need for more emphasis on preventive and, especially, promotive mental health measures, as well as the active inclusion of low- and middle-income countries in future research.