Integrating One Health Into Health Systems: A Systematic Review and Narrative Synthesis of Implementation Challenges, Opportunities and Strategic Directions

Background The One Health (OH) approach, which gained international prominence in the early 2000s and was formally articulated through a unified definition in 2022, promotes coordinated action across human, animal and environmental health sectors. Despite increasing global recognition, its integration into national health systems remains inconsistent. This review synthesizes global evidence on challenges, opportunities and strategic directions for embedding OH within health system structures. Study Design A systematic review with narrative synthesis. Methods This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) 2020 guidelines. Peer‐reviewed studies published between 1 June 2013, and 1 April 2025 were identified through searches conducted in January–February 2025 in Scopus, PubMed, Web of Science and ProQuest Health and Medicine. Supplementary searches included Google Scholar and backward reference screening. Two reviewers independently screened studies and applied predefined eligibility criteria. Findings were synthesized narratively. Results Of 2606 records identified, 17 studies were included. The studies represented Africa, Europe, Asia, Australia and multi‐country settings across varying income levels. Key challenges included weak governance arrangements, limited legal and policy support, inadequate financing, workforce capacity constraints and persistent sectoral fragmentation. Opportunities were linked to heightened awareness of zoonotic threats and antimicrobial resistance, growing institutional endorsement, academic engagement and emerging multisectoral coordination mechanisms. Conclusion Sustainable integration of OH requires embedding it within governance, financing and service delivery systems rather than implementing it as parallel initiatives.