Oyo is the name for a city in Africa and also the loose empire which that city controlled in the 17th and 18th centuries.

What was to become the Oyo empire began as the state of Oyo, which was founded sometime before 1400, with its capital at Oyo Ile, (also known as Katunga or Old Oyo). Rising to preeminence through wealth gained from trade and through the possession of a powerful cavalry, the Oyo Empire was the most politically important Yoruba state between the mid-17th and late 18th century, holding sway not only over the lesser Yoruba states, but also over the Fon kingdom of Dahomey (which was located in the state now known as the Republic of Benin.)

In 1796, an Ilorin-centred revolt against Awole , the then-reigning Alaafin , or chief-ruler of Oyo, was initiated by Afonja , the Aare Ona Kakanfo , or chief military commander of the army. This revolt, which led to the secession of Ilorin, marked the beginning of the disintegration of the Oyo empire, as other vassal states soon began to follow Ilorin's example. The enlistment to his cause by Afonja of an itinerant Fulani scholar of Islam called Alim al-Salih , in the hope of thereby securing the support of Yoruba muslims and volunteers from the Hausa-Fulani north, eventually led to the razing by the Fulani Empire of Oyo Ile in 1835, and with it, the demise of the Oyo Empire.

Oyo is also a city in the Republic of Congo.