ABSTRACT Objective Although school is considered a suitable space for health promotion, there have been difficulties adopting healthy eating practices due to many ultra-processed foods offered in school canteens and irregularities in Food and Nutrition Education actions. This study aimed to propose a certification seal to encourage school canteens’ managers in Brazil to adopt actions for the Promotion of Appropriate and Healthy Diets. Methods It is a methodological study in which the “Healthy Canteen Certification Seal” was developed, containing ten guidelines based on the Dietary Guidelines for the Brazilian Population. The instrument was built based on national and international documents and later was consensually agreed upon by experts using the Delphi method. Results Ten guidelines for the Seal were developed around the following topics: the creation of a Council, availability of written and accessible standards; stimulation of water intake; offer of natural foods, limitation of processed and ultra-processed foods, promotion of educational actions, prohibition of abusive food advertisements, structural changes, and staff training. The overall evaluation of the proposal by the experts was positive concerning its relevance, and more than 70% of positive results were attained for all guidelines. The participants agreed that the Seal would contribute to expanding and enhancing healthy eating practices in schools. Conclusion We believe that this proposal will encourage educational institutions to adopt and implement actions for the Promotion of Appropriate and Healthy Diets, thus contributing to ensuring Food and Nutrition Safety for students.