This innovation and practice report examines the achievements and challenges of the development and implementation of two policies guiding climate adaptation and mitigation action in Thailand’s healthcare system, namely 1) The GREEN and CLEAN hospitals policy, and 2) The Health National Adaptation Plan. Based on key informant interviews and focus groups it was found that at the government level adaptation and mitigation planning was well developed. However, adaptation planning could be strengthened at the organisational level. Social values such as strong leadership and a sense of shared ownership significantly influenced initiative outcomes. Sub-district public health officials also served as crucial intermediaries between the government and local communities however, strengthening the coupling of environmental monitoring data with health impact analysis could further policy progression in the adaptation space. Participants also highlighted the need for increased funding, improved training, and greater knowledge sharing. Other healthcare systems could learn much from Thailand’s approach to tackling climate change and health, particularly in the benefits of a detailed health-focused national mitigation and adaptation policy; establishment of local public health units; encouraging a sense of shared ownership; and, conceptualising environmental sustainability as core to healthcare.