Oyo, usually referred to as Oyo State to distinguish it from the city of Oyo, is an inland state in south-western Nigeria, with its capital at Ibadan. It is bounded in the north by Kwara State, in the east by Osun State, in the south by Ogun State and in the west partly by Ogun State and partly by the Republic of Benin.

Oyo State was formed in 1976 from Western State, and included Ọsun State, which was split off in 1991. Oyo State is homogenous, mainly inhabited by the Yoruba ethnic group who are primarily agrarian but have a predilection for living in high-density urban centers. The indigenes mainly comprise the Oyos, the Oke-Oguns, the Ibadans and the Ibarapas, all belonging to the Yoruba family and indigenous city in Africa. Ibadan had been the centre of administration of the old Western Region since the days of British colonial rule.

Other notable cities and towns in Ọyọ State include Ọyọ, Ogbomọsọ, Isẹyin, Kisi, Okeho, Saki, Eruwa, Iroko, Lanlate, Oje-Owode, Sepeteri, Ilora, Awe, Ilero, Igbeti, Igboho and Igbo-Ora, Otu.