Thailand is the home of 66.4 million people of which 17.21% are children aged 0-14 years. The total population of children has decreased from 20.23% in 2009 to 17.21% in 2018. The mortality ratio of infants and children under 5 years of age has also steadily decreased between 2008 and 2017. Urbanization, globalization, and industrialization appear to be the main contributors to the transition from infectious to chronic non-communicable diseases. The main types of environmental exposure to children are water, sanitation and hygiene, air pollution from traffic in inner cities, chemical hazards from pesticides which result from agricultural activities in countryside areas, heavy metal contaminants such as lead and arsenic from anthropogenic activities, e.g. from industrial zones, mining, electronic appliance waste, and ongoing climate change. It is concluded that economic development and rapid urbanization in Thailand have resulted in environmental degradation and pose a risk to children's health. Future development and implementation of measures to improve children's environmental health (CEH) in the country are needed. Some examples include research specific to environmental threats to children's health; international environmental health networks to share experience and expertise; and solutions to solve the problems.