<![CDATA[Background: Anemia among adolescent girls adversely affects cognitive performance, physical growth, and future reproductive health, potentially increasing stunting risk in the next generation. Despite widespread iron supplementation programs, adherence remains low. Schools provide a strategic setting for systematic adolescent health interventions. Objectives: This study aimed to identify the effectiveness of school-based interventions in improving iron supplementation adherence among adolescent girls aged 10–19 years. Methods: A systematic review was conducted following PRISMA guidelines using Rayyan software. Literature published between 2014 and 2025 was retrieved from five international databases, namely Cochrane Library, Medline, PubMed, ScienceDirect, and Scopus. Among the 493 screened publications, seven studies met the inclusion criteria. Data were synthesized using tabular and thematic approaches, together with a framework-based synthesis to categorize interventions according to educational strategies and supplementation methods. Results: Interventions were categorized into active learning-based education and education integrated with iron supplementation. All interventions improved adherence by 22–27%, while combined education and supplementation increased hemoglobin levels by 0.5–1.0 g/dL. Interventions also improved knowledge and attitudes toward anemia prevention. Teacher involvement was a key factor supporting implementation, whereas peer and parental engagement remained limited. Conclusions: School-based interventions integrating contextual education, digital methods, and iron supplementation effectively improve iron supplementation adherence and hemoglobin status among adolescent girls. However, the limited number of studies and heterogeneity of intervention designs should be considered. Future research and policies should strengthen collaboration among schools, families, and communities to support sustainable anemia prevention. ]]>
