<p>This study examined the emergence of a sustainable timber construction ecosystem across the forest-to-building value chain, using Sweden as a mature benchmark and Thailand as an early-stage socio-technical transition case. A qualitative methodology was adopted, combining document analysis, site observations, and semi-structured interviews with actors across upstream, midstream, transitional, and downstream sectors. The findings revealed significant misalignments operating at multiple scales: at the macro level, insufficient policy coordination and the absence of a demand-driven strategy impeded transition momentum; at the meso level, fragmented value chain coordination and technical standardisation gaps undermined sector cohesion; and at the micro level, socio-cultural embeddedness shaped how forests were understood, primarily as livelihood resources rather than as construction material sources, presenting a distinctive barrier in the Thai context. Critically, these misalignments were interconnected, with each level reinforcing the others rather than acting alone. As Thailand’s timber construction ecosystem was found to be in an early stage of development, this study also identified the critical mediating role of transition actors positioned between forest management and the built environment, enabling diverse construction pathways, including reclaimed wood, plantation-sourced solid wood, tropical-adapted engineered wood products, and hybrid structural systems. These findings contribute to sustainability transition theory by foregrounding the specificities of tropical contexts, while offering practical guidance for policymakers, industry stakeholders, and researchers working toward timber construction ecosystems in emerging economies.</p>