Mangrove forests represent one of the most complex socio-ecological systems in the world, simultaneously functioning as ecological buffers, sources of livelihood, and arenas of institutional contestation. Despite their recognized ecological and economic value, mangrove ecosystems continue to experience rapid degradation, particularly in developing coastal regions where property rights are ambiguous and governance arrangements are fragmented. This article develops an integrative theoretical and empirical analysis that bridges agency theory and institutional perspectives with community-based natural resource management in mangrove ecosystems. Drawing strictly on classical agency theory literature and an extensive body of mangrove governance and conservation studies, the paper conceptualizes mangrove management as a multi-layered principal–agent problem embedded within dynamic socio-ecological systems. Through a qualitative synthesis of institutional arrangements, property rights regimes, and participation mechanisms documented across Southeast Asia and other developing regions, the study elucidates how agency costs, information asymmetries, and incentive misalignments shape management outcomes. The results demonstrate that mangrove degradation cannot be adequately explained by ecological pressures alone; rather, it is deeply rooted in institutional failures, conflicting mandates, and weak accountability structures. Conversely, cases of successful mangrove conservation reveal the importance of devolved governance, community participation, and adaptive institutional design that aligns incentives between state agencies, local communities, and resource users. The discussion advances a theoretically grounded framework that integrates agency theory with socio-ecological resilience and common-property governance, highlighting limitations and future research directions. The article contributes to environmental economics, institutional analysis, and natural resource governance by offering a unified analytical lens for understanding and improving mangrove forest management in developing coastal contexts.