["Environmental Policy and Governance, EarlyView. ", "\nABSTRACT\nThe sound formation of robust environmental policies is increasingly important for low‐ and middle‐income countries (LMICs) to achieve their national objectives and international commitments. However, policy implementation can be complex, and environmental policies may not be prioritised given other critical socio‐economic development issues. Thus, although the formation of environmental policies is an important goal, effective and timely implementation is essential to ensure a policy achieves its desired outcomes. Existing studies frequently note that environmental policy implementation gaps exist, but synthesis of the evidence has so far been limited in LMIC contexts. As such, this review seeks to synthesise documented cases of environmental policy implementation gaps in LMICs, focusing on nationally directed policies. A total of 67 academic articles were reviewed, leading to the identification of five themes, which represent factors that contribute to policy implementation gaps. These relate to: the policy content; institutional arrangements and interactions; resource availability; engagement of non‐governmental actors; and the political interests and dynamics. These factors are interrelated and interacting, and context dependent. Identifying these common causes of implementation gaps provides a foundation for future analysis, but also points to factors worthy of consideration when designing policies. Hence, this review is of value to academics, policymakers and other practitioners working on environmental policy issues in LMICs.\n"]