Thailand's pioneering national climate investment taxonomy, launched in July 2023, is the most comprehensive framework for climate-aligned investment classification in Southeast Asia. It introduces global innovations such as aquaculture guidance and a traffic light classification system for economic activities. The taxonomy's phased implementation, starting with energy and transportation sectors and expanding to cover nearly 95% of emission-relevant activities by Phase II, aims to steer capital towards Thailand's net-zero ambitions by 2065. Developed through collaboration with various organisations, this framework demonstrates strong alignment with international and regional standards like the EU and ASEAN taxonomies, positioning Thailand as a leader in sustainable finance and providing a model for other developing economies.