Animism used to be popular throughout Southeast Asia. Since the early A.D, Buddhism and Brahmanism began to influence the area, leading to the emergence of civilizations glowing from the 7th century to the 12th century, leaving many outstanding religious temples such as Angkor in Cambodia, Borobudur and Prambanan in Indonesia, Bagan in Myanmar.

From the 13 century, Islam arrived in Southeast Asia with Middle East merchants, Missionaries from Europe evangelized Catholicism here from the 15th century.

Today, Mahayana Buddhism is prevalent in Singapore; Theravada Buddhism is popular in Thailand, Laos, Cambodia, Myanmar; Islam is predominant in Indonesia and is the national religion of Brunei and Malaysia. Catholicism is popular in the Philippines, and Hinduism is concentrated in Bali.

All of the four religions are widespread in plains and coastal areas, meanwhile many residents in the mountainous areas continue practicing indigenous beliefs. Religions arrived in Southeast Asia have absorbed several features of local belief and cultures.