The relatively rapid expansion of protected areas (PAs) has outpaced their effective governance, monitoring, and evaluation processes, resulting in a knowledge gap, particularly in relation to the impact and efficacy of co-managed protected areas in conserving biodiversity globally. Bangladesh, like numerous other nations, is expanding its existing co-management model to incorporate additional PAs while simultaneously making only limited modifications to the management of these protected areas. Evaluations, however, are relatively rare throughout the world, including Bangladesh, despite their potential to improve PA quality and effectiveness. The purpose of this article is to examine current co-management practices at two sites in Bangladesh’s Sundarbans to identify significant challenges and the efficacy of co-management initiatives through the establishment of a novel evaluative framework. The primary empirical data collection methods included key informant interviews, stakeholder consultation in focus group discussions, and uncontrolled personal observation. Despite significant progress in terms of policy and legislative reforms, many issues remained unattended, such as a goal of balancing conservation and development, increasing locals’ say in decision making, access to resources, and establishing strong institutions. This addition is believed to aid in reconciling the local community and the government. We also need to give more weight to such things as accounting and transparency, income diversification, and showing respect for preexisting social norms. The problems raised in this article are thought to be significant in bridging the gap between management plans and actual management of PAs, not just in Bangladesh but also in other regions of the world that use co-management to achieve sustainability.