Area-based conservation interventions carry the risk of leakage, where agricultural or forestry activities are displaced beyond intervention boundaries, potentially undermining biodiversity and climate benefits. However, conservation practitioners' views on its significance and mitigation measures remain unclear. To address this, we conducted an online survey of practitioners involved in area-based tropical ecosystem conservation and management. Over one-third of sampled practitioners were unaware of the concept of leakage, and half were unconcerned. Only 47% implemented mitigation measures, classified as agricultural intensification, income-enhancing, and conservation-enhancing measures. Despite 85% believed their measures were effective, limited evidence of monitoring suggests some of these claims might be speculative. While 60% did not view agricultural intensification as harmful, financial constraints were the most cited barrier to implementation. These findings reveal a troubling disconnect between practitioners’ perceptions and the potential scale of leakage, emphasising the need for more rigorous accounting to meet global biodiversity and climate goals.