A disaster early warning system is an important tool to prevent a large number of human casualties from natural disasters such as earthquakes and tsunamis. In Thailand, an early disaster warning system has been established as a part of the reconstruction process after the 2004 Indian Ocean earthquake and tsunami. This chapter focuses on the establishment, development and management process of this early warning system, with particular emphasis on tsunami hazards. This study considers face-to-face interviews with executive officers from the National Disaster Warning Center (NDWC) and the Seismological Bureau of the Thai Meteorological Department (TMD). Moreover, observations of a warning drill conducted in September 2013 in Bangkok, Thailand are also considered. Relevant issues and findings are discussed while providing suggestions for the potential development of early warning systems of a similar nature in other developing countries.