Obesity has become one of the biggest public health problems of the 21st century. Prevalence of obesity in children and adolescents has increased dramatically worldwide over the last 20 years, and this trend is expected to continue. Obesity in childhood is concerning as it predicts obesity in adulthood, a common risk factor for a wide array of chronic diseases and poor health outcomes. Obesity is preventable and a vast but fragmented body of evidence on preventative interventions is now available. This article outlines the protocol for a scoping review of published literature reviews on interventions to prevent obesity in children. The scoping review addresses the broad research question 'What is the evidence on interventions to prevent childhood obesity?'. It aims to give an overview of the various interventions available, understand those which are effective and identify barriers and facilitators to their effectiveness. The six-staged Arksey and O'Malley methodology framework is used to guide the scoping review process: following the definition of the research questions (stage 1); the eligibility criteria and search strategy are defined (stage 2); the study selection process based on the eligibility criteria identified will follow (stage 3); a framework developed for this review will then inform the extraction and charting of data from the included reviews (stage 4); results will be aggregated and summarised with criteria relevant for health professionals and policy-makers (stage 5); and the optional consultation (stage 6) exercise is not planned. Since the scoping review methodology aims at synthetising information from available publications, this study does not require ethical approval. An article reporting the results of the scoping review will be submitted for publication to a scientific journal, presented at relevant conferences and disseminated as part of future workshops with professionals involved in obesity prevention. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.