Body ideals conveyed by the media and by body comparisons often result in body dissatisfaction, which can cause risky health behaviours and eating disorders, especially in adolescents. We conducted a meta-analytic review of existing school-based interventions designed to enhance media literacy in order to reduce body dissatisfaction and to promote a positive body image. We included controlled trials examining children and adolescents from grade five to nine (age 10–15 years) after a manual search and a comprehensive literature search using PsycINFO, Medline, Web of Science, and CENTRAL. We computed average weighted effect sizes (Hedges’ g) with the help of a random effects model and identified seventeen different programme evaluations with 7392 participants. We found a significantly larger effect on positive body image and media literacy in the intervention compared to control groups. However, heterogeneity was substantial for both outcomes. Results suggest that media literacy interventions have the potential to improve media literacy and reduce body dissatisfaction. Interventions that worked with the principle of induction of cognitive dissonance were the most effective.