<p>Climate change is increasingly recognized as a driver of unequal health risks, yet empirical evidence examining how these risks are shaped by structural vulnerabilities and institutional responses among migrant populations remains limited. Addressing this gap, this study examines climate change and migrant health in Thailand, focusing on how institutional stakeholders understand the structural conditions and response capacities that shape health risks and access to care. Thailand represents a critical case due to its high climate exposure and large, diverse migrant workforce, including workers concentrated in climate-sensitive sectors such as construction, agriculture, fisheries, and domestic work. The study adopts a qualitative, systems-oriented design, combining an organisational readiness assessment adapted from the Capacity Assessment Tool for Climate Action Transparency with a semi-structured focus group discussion involving stakeholders from policy, implementation, civil society, and academic settings working with migrant populations. Anchored in the Intergovernmental Panel on Climate Change risk framework and the social determinants of health, the analysis conceptualizes climate-related migrant health risk as the interaction of hazard, exposure, vulnerability, and institutional response, and examines both direct health impacts and indirect pathways mediated through social, economic, legal, and institutional conditions. The findings suggest that climate-related health risks among migrants are intensified by precarious employment, hazardous housing, insecure documentation, language barriers, and weakly coordinated service systems. The organisational readiness assessment further indicates moderate-to-low institutional preparedness, particularly in surveillance, monitoring, and cross-sector coordination. A central finding is that institutional capacity remains limited and insufficiently aligned with the chronic, cumulative, and socially mediated nature of climate-related migrant health risks. The study contributes empirical and conceptual insight to climate–migration–health scholarship by demonstrating how structural inequalities and institutional responses jointly shape migrant health outcomes in climate-vulnerable settings.</p>