Tropical and subtropical forests and savannas support millions of forest-dependent people. These ecosystems are under rising pressure from deforestation, primarily due to agricultural expansion. Yet, a large proportion of agriculture-driven deforestation does not lead to productive land use afterwards, potentially because of speculative, halted, or abandoned land investment projects. Our understanding of such apparently failed projects, their links to deforestation, and their impact on local people, however, remains limited. Here, focusing on failed land investment projects in tropical and subtropical woodlands (i.e., forests and savannas), we aim to understand how these projects failed, how they led to deforestation, and how access to land for local communities changed after failure. We identified and reviewed cases of failed projects that led to deforestation sourced from a systematic literature review and global databases on land investments and environmental conflicts. Our results show that resistance to land investment projects was the most common determinant of failure, suggesting prevailing misalignment of investments with local needs. We identified various configurations on how failed projects are linked to woodland loss, ranging from land clearing for an eventually abandoned project to illegal timber harvesting. Most of the projects targeted areas used by local, forest-dependent communities. Despite failure, some of these communities lost access to lands in the process, indicating that even failed projects can result in land grabs. Our multi-case analysis revealed the pivotal roles played by governments, socioeconomic agendas, and investors in these complex predicaments. This emphasizes the need to learn from failed projects to reevaluate priorities in land governance, enhance government enforcement capabilities, and adopt a more inclusive and comprehensive approach that amplifies local voices and safeguards tropical and subtropical woodlands.