ASEAN countries have high potential for developing biomass energy from wastes and wastewater. Biogas is one of the renewable energy sources that can be used as both heat and electricity. The aim of this paper is to present the current status of biogas technology, biogas purification technology and biogas utilization in Thailand. Biogas utilization at the domestic level has met with varying success, both in Thailand and other nations. Key to success in Thailand has been the focus on treating agricultural and agro-industrial waste streams, with biogas being a useful byproduct of this approach. The data was collected from primary and secondary sources from interviews with technology vendors, technology users and policy makers in Thailand. This paper gives an overview of the development of biogas technology and measures and strategies in promoting biogas production and utilization, as well as providing a successful model to increase biogas utilization in cassava starch industries due to a high success output. Since 1984, anaerobic wastewater treatment has been developed to produce biogas in cassava starch factories. At the beginning, most factories were not interested to invest in biogas production due to the high investment cost. However, this changed radically with the introduction of new measures and strategies such as financial support, tax incentives, small power purchase tariff (SPP) and environmental law enforcement. The key success factors to promote biogas utilization are the result of four important approaches, policy, technology, incentives and maintenance.