Extreme heat, often called a ‘silent killer,’ poses significant threats, particularly in Southeast Asia, where rapid urbanisation and increasing population density exacerbate vulnerability. Populations in this region face heightened risks of heat-related mortality and illness, as well as diminished efficiency of the energy systems essential for cooling. Additionally, limited financial resources impede cities’ adaptation efforts, establishing finance as a critical factor influencing vulnerability to extreme heat. Despite growing recognition of the necessity for climate adaptation and mitigation financing, as highlighted by the Sendai Framework for Disaster Risk Reduction and the outcomes of the Conferences of the Parties to the United Nations Framework Convention on Climate Change, the adaptation finance gap continues to widen. This review article examines the literature on potential structural and non-structural adaptation strategies for extreme heat and identifies financing opportunities in Southeast Asia, thereby contributing to the Priority 3 agenda of the Sendai Framework. The review concludes with three recommendations: promoting assessment tools to increase adaptation finance and facilitate adoption, addressing issues of maladaptation related to adaptation finance, and aligning adaptation finance with long-term investment benefits.