Iwo, city, southwestern Nigeria, in Osun State, near Ibadan. It is a center for the production of cocoa and traditionally dyed cotton textiles. Iwo became the capital of a Yoruba kingdom in the 17th century and grew rapidly when many refugees from the Yoruba civil wars of the 19th century settled here. It was under British control from the 1890s to 1960. Population (1995 estimate) 353,000.