Animism was the first religion in Tanzania. This practice is rooted in numerous beliefs and accompanied by worship and rituals stemming from ancient African traditions. However, with the arrival of Germans and English colonizers, most tribes converted to Christianity, primarily Protestantism. Yet they did not entirely abandon the religion of their ancestors. This gave rise to a form of syncretism between Christianity and animism. Beyond Christianity, Islam also claims a substantial following, particularly along the Indian Ocean coast and on the island of Zanzibar.

According to estimates, 62% of Tanzania's total population is Christian. The main tribes that embraced this faith are the Sukuma, Makonde, Nyamwezi, Chagga, and Haya. Islam, for its part, represents 35% of the population, with the vast majority (99%) living on Zanzibar island. Only a few tribes such as the Maasai and Datooga continue to practice traditional animism.