The cognitive and social practices associated with critical health literacy, such as critical appraisal of health messages and participation in political processes to address wider determinants of health, are of lifelong benefit. Understanding how and where critical health literacy development can be supported early in the life course may improve health outcomes now and in the future. This scoping review focuses on how critical health literacy in children is conceptualized and the supportive environments available for its development. Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines are used in reporting. Evidence retrieved was eligible for inclusion if it contained a substantive conceptual or empirical study of critical health literacy in populations aged 7–11 (middle childhood). From the included 18 peer-reviewed and grey literature sources, schools are identified as the setting most associated with the development of critical health literacy in the target age group. However, the action-oriented dimension of critical health literacy is rarely supported in the school setting. The review concludes that further research is needed to clarify how and where to support children to develop critical health literacy in and outside of school settings.