Halting and reversing global forest loss is a key priority for sustainable development pathways. Multiple countries in the Global South have recently transitioned from net forest loss to net forest gain. Understanding and explaining reforestation patterns is necessary to better understand land cover dynamics and create more effective sustainability policies. We show that international migration – a key feature of globalization in the 21st century – spurs a transition to greater forest cover in Nepal. Although some aspects of globalization – agricultural commodity production and trade in particular – have been identified as contributing to deforestation, the effects of international migration are less well understood. Using data from Nepal’s national census (1.36 Million households) and from high-resolution forest cover change, we find that international outmigration is associated with substantial increases in local forest cover, even after controlling for multiple confounding factors. We find that areas with international outmigration levels above the median in 2001 were 44% more likely to experience net reforestation between 2000–2012. This effect of outmigration is mediated by changes in population density and in household agricultural activity. Effects of outmigration are higher in more agriculturally suitable areas, suggesting that migration-driven forest transitions are influenced by agricultural production systems. We provide new empirical evidence of forest transition driven by international migration and a generalizable analytical approach to the study of forest transitions using secondary global and national datasets. Our results suggest that actions to reach global sustainability, biodiversity targets, and reduced emissions can be better designed and targeted by taking into account the effects of international migration on natural resources and ecosystems.