Recent years have seen a burgeoning interest in integrated landscape approaches to “reducing emissions from deforestation and forest degradation” (REDD+) that can address emissions drivers associated with land use change. However, there are often significant institutional challenges for the design and implementation of integrated policies in practice. There are also few scholarly examples of integrated landscape approaches to REDD+, particularly at subnational levels, and little is known about how or why they have emerged. To address this gap, this article explores the evolution of an integrated landscape approach to REDD+ in Vietnam through the lens of policy design and policy learning. Our research was structured around three objectives: 1) Investigate challenges for the design and implementation of intra and inter-sectoral policies at national and subnational levels of REDD+ governance 2) Explore how these challenges have led to policy change and improved policy integration 3) Evaluate if policy changes represent shallow or “deep” forms of policy learning. We found that limited policy capacity, problematic policy design processes, and bureaucratic politics have been significant barriers for vertical and horizontal policy integration. However, initial challenges have also led to instrumental and social policy learning, evident in changes to policy tools, goals, targets, and agents. We found that a regional landscape approach that leverages existing state institutions has emerged because it allows REDD+ actors to exploit scarce resources for design and implementation. We conclude that existing state policies and political commitment are essential for realizing an integrated landscape approach to REDD+, but that the process of REDD+ implementation may also contribute to “deeper” policy learning among state actors, and substantive reforms in state institutions.