Five Southeast Asian countries (Thailand, Vietnam, Laos, Philippines and Malaysia) have experienced forest transitions, that is, a shift from net deforestation to net increases in forest area, since the 1990s. Climate change mitigation policies such as REDD+ actively promote reforestation, especially in the Global South, where they have been accompanied by exclusionary effects, known as green grabbing. In a regional analysis, we highlight some of the political and biophysical dimensions that come along with forest transitions in the five Southeast Asian countries, interrogating these with respect to the spatial injustices they produce. We propose to read forest transitions as a combined process of separating and industrializing agriculture and forestry – at the expense of more integrated land use such as shifting cultivation. We use the concepts of state territorialization and socio-ecological transition to analyze the separation of agricultural and forest land, an eventual marginalization of shifting cultivation and an increasing use of fossil energy carriers (that enables the industrialization of land use and other economic activities). These complex processes attenuate and compromise acclaimed benefits of the forest transition for climate change mitigation.