Buddhism in Thailand is largely of the Theravada school, which is followed by roughly 93.4 percent of the population. Thailand has the second largest Buddhist population in the world, after China, with approximately 64 million Buddhists. Buddhism in Thailand has also become integrated with folk religion (Bon), Hinduism from millennia of Indian influence, and Chinese religions from the large Thai Chinese population. Buddhist temples in Thailand are characterized by tall golden stupas, and the Buddhist architecture of Thailand is similar to that in other Southeast Asian countries, particularly Cambodia and Laos, with which Thailand shares cultural and historical heritages. Thai Buddhism also shares many similarities with Sri Lankan Buddhism. Thailand, Cambodia, Myanmar, Sri Lanka and Laos are countries with Theravada Buddhist majorities.

Dhammayuttika Nikāya, or Dhammayut Order, is an order of Theravada Buddhist bhikkhus (monks) in Thailand, Cambodia, and Burma, with significant branches in the Western world. Its name is derived from Pali dhamma + yutti + ka (group). The order began in Thailand as a reform movement led by a prince who would later become King Mongkut of Siam, before also spreading to Cambodia and Burma. The movement became formally recognized as its own monastic order by the Thai government in 1902, with any Thai Theravada bhikkhus not within the order being referred to as part of the Maha Nikaya order. The Dhammayuttika Nikaya plays a significant political role in Thailand. The order has historically been favored by the Thai government and monarchy, with the order holding the majority of all royal monastic titles in Thailand and most of the Supreme Patriarchs since its founding having come from the Dhammayuttika Nikaya, despite the order making up less than ten percent of all bhikkhus in Thailand.