The use of digital technologies for health has been rapidly gaining ground in the last decade, including as a strategy to empower adolescents living in urban resource-constrained settings. Nevertheless, unclarity and incoherence remain regarding which programme strategies generate which outcomes, as well as regarding the importance of context. We set out to answer the question "How do digital empowerment strategies work to improve adolescent health and well-being?". We conducted a realist-informed review, the first on this subject matter to our knowledge. The realist methodology is geared towards the understanding of socially complex interventions, such as digital empowerment. We synthesized the data into a programme theory uncovering social mechanisms and context conditions underlying specific programme strategies. We found that digital technologies enlarge the space for adolescents to access information to health services on their own terms and provide anonymity, which leads to a sense of safety if access is not curbed by gatekeepers. If adolescents have access to information adapted to their needs, they will be able to make informed decisions, and this will contribute to improved health outcomes because their better understanding enlarges their sense of individual agency. We identified two main gaps in the literature on digital interventions for adolescents. Both are related to an under-theoretisation of the concepts the programmes rely on in implementation: (1) the urban environment the programme has to operate in and its meaning for the adolescents; (2) the socio-developmental stage of the adolescents the programmes work in.