Theravada Buddhism is the predominant religion in Cambodia, and about 95% of the population practices the religion.Many other Southeast Asian countries also practice Buddhism, which began around the … However, Christianity and Cham Muslim are being active and popular among a large number of population as well in the capital and provinces, showing a sign of growth. The Khmer, who have lived in what is now Cambodia since the 9th century, are the dominant ethnic group in Cambodia. Buddhism in Cambodia Thearavada Buddhism is the official religion in Cambodia which is practiced by 95 percent of the population-- just like that of Thailand, Burma, Sri Lanka. The population of Cambodia is approximately 95 percent Theravada Buddhist, as high a percentage as anywhere in Asia.Cambodian Buddhism is associated with the historic Ankgor Wat temple, a jewel of Khmer civilization. Venerable Maha Ghosananda was a product of Cambodia's Theravada Buddhism and perhaps the greatest known exemplar of Cambodian spirituality. It is worthwhile to contemplate how remarkable a human being Maha Ghosananda was, and to consider that he was born from the very heart of Cambodian culture, the Buddhist monastic system. Understanding Cambodian religion is crucial to understanding and appreciating Cambodia. The temple complex is the largest religious monument in the world at 420 acres (0.65 square miles). Theravada Buddhism in Cambodia The front side of the main complex of Angkor Wat (from Khmer meaning Capital Temple). After all, Angkor Wat temple is a religious building.