Mental health problems are a leading cause of health-related disability among children and adolescents. Organized activities are a possible preventive factor for mental health problems. An aggregated overview of evidence is relevant for youth policymakers and is lacking so far. Thus we aim to provide an overview of published systematic reviews and meta-analyses on the impact of participation in organized sport and non-sport activities (e.g. arts, music) on childhood and adolescent mental health. Systematic reviews were identified through a search in five databases (Embase, MEDLINE, Web of Science core collection, CINAHL and PsycINFO) on 25-March-2021. Systematic reviews about organized activities and mental health outcomes in 0-21-year-olds published in English were included. Two independent reviewers assessed titles, abstracts and full texts, performed data-extraction and quality assessment using the AMSTAR-2 and assessed the quality of evidence. Out of 833 studies, six were considered eligible. Quality of the reviews ranged from critically low to moderate. Most reviews focused on organized sport activities, focusing on: team sport, level of sport involvement, extracurricular and community sport activities. Indications of a positive impact on mental health outcomes were found for participation in team sport, in (school) clubs, and in extracurricular and community sport and non-sport activities. We found a small positive impact of organized sport activities on mental health outcomes among children and adolescents. This seems not to depend on any specific type of organized sport activity. Limited evidence was found for organized non-sport activities.