The aim of the thesis investigates and addresses what strategies municipalities can use in relation to collaborative action in a collaborative governance setting to facilitate heat transition at regional scale. The heat transition is a multifaceted problem where fragmentation and a deficient direction role of municipalities is a key institutional challenge. To address the problem, regional energy strategies are established to collaborate with state and non-state stakeholders, but the heat transition is still stagnating today. Collaborative governance is a governing arrangement that engages public and non-public organizations in a collective decision-making process to implement public policy to resolve social-technical problems. However, today the application of the collaborative governance theory is scarce on sustainable transformation. For this reason, the author decided to apply a collaborative governance lense on the current situation for heat transition. The thesis first examines the collaborative governance framework, which is the most suitable to apply in relation to heat transition. In the second step, the selection of a comparative empirical research methodology is selected. Third, two RES regions with rural characteristics are investigated to get insight into the current situation. Lastly, the empirical findings are discussed in relation to current collaborative governance literature and governmental policy. Finally, recommendations for municipalities and other regional stakeholders can be provided. The empirical findings show that collaborative governance conditions are rarely present to facilitate the heat transition at regional scale. The author identified crucial conditions within the system context and collaborative governance process itself, which is explainable by the iterative nature of the model. The conditions include the current deficient policy and legal framework, high level of contention among citizens, inadequate resource conditions. In the collaborative governance regime itself this results in lack of interdependence, trust and high level of uncertainty, through which no shared interest or common language are practiced. The thesis concludes with recommendations for the regional collaboration regarding heat transition for practitioners and for future research on collaborative governance.