Efforts to combat global climate change through forestry plantations designed to sequester carbon and promote sustainable development are on the rise. This paper analyses the trajectory of Cambodia´s first large-scale reforestation project awarded within the context of climate change mitigation. The 34,007 ha concession was formally conceived to promote sustainable resource use, livelihood improvements and emission reduction. On the ground, however, vast tracks of diverse forest landscapes are being cleared and converted to acacia monocultures, existing timber stocks are logged for market sale, and customary land users dispossessed from land and forest resources. While the project adds to an ongoing land grab crisis in Cambodia, we argue that the explicit environmental ends of the forestry concession enabled a ‘green grab’ that not only exceeds the scale of land grabs caused by conventional economic land concessions, but surprisingly also exacerbates forest logging and biodiversity loss in the area. This case demonstrates the extent to which current climate change discourses, forestry agendas and their underlying assumptions require critical revision in global policy discussions to forestall the growing problem of green grabbing in land use.