This report presents lessons learned from the “Promotion of Well-being in Schools in Southeast Asia” programme, implemented by SEAMEO SEPS in collaboration with the Southeast Asia One Health University Network (SEAOHUN) and supported by Chevron. The programme strengthened school meals, student nutrition, hygiene, and sustainable food environments through One Health, Sufficiency Economy Philosophy, and sustainability approaches. Drawing from seven grantee schools and one volunteer school in Southeast Asia, the report highlights school-led solutions, community engagement, good practices, challenges, and recommendations for building healthier, more resilient, and sustainable schools.