The market for commercially produced complementary foods (CPCF) is rapidly expanding in Southeast Asia. However, a legal and policy desk review co-authored by Alive & Thrive found that existing national binding legal measures for CPCF in seven countries (Cambodia, Laos, Indonesia, Malaysia, the Philippines, Thailand, and Viet Nam) are insufficient. While each country has at least two relevant legal measures, there is limited alignment with Codex Alimentarius and WHO guidance on CPCF nutrient composition and labeling. None of the countries fully align with relevant Codex standards, and only one fully aligns with WHO recommendations, indicating an urgent need to strengthen and enforce legal measures to ensure nutritionally adequate and responsibly labeled CPCF for children age 6–36 months. The study suggests improved, comprehensive, and enforceable national binding legal measures for CPCF to ensure that countries protect, promote, and support optimal nutrition for older infants and young children.