Aztec religion is the Mesoamerican religion practiced by the Aztec empire. Like other Mesoamerican religions, it had elements of human sacrifice in connection with a large number of religious festivals which were held according to patterns of the Aztec calendar. It had a large and ever increasing pantheon; the Aztecs would often adopt deities of other geographic regions or peoples into their own religious practice. Aztec cosmology divided the world into upper and nether worlds, each associated with a specific set of deities and astronomical objects. Important in Aztec religion were the sun, moon and the planet Venus—all of which held different symbolic and religious meanings and were connected to deities and geographical places.

Large parts of the Aztec pantheon were inherited from previous Mesoamerican civilizations and others, such as Tlaloc, Quetzalcoatl and Tezcatlipoca, were venerated by different names in most cultures throughout the history of Mesoamerica. For the Aztecs especially important deities were Tlaloc the god of rain, Huitzilopochtli the patron god of the Mexica tribe, Quetzalcoatl the culture hero and god of civilization and order, and Tezcatlipoca the god of destiny and fortune, connected with war and sorcery. Each of these gods had their own temples within the Aztec capital Tenochtitlan--Tlaloc and Huitzilopochtli were both worshipped at the Templo Mayor. A common Aztec religious practice was the recreation of the divine: Mythological events would be ritually recreated and living persons would impersonate specific deities and be revered as a god—and often ritually sacrificed.