Iseyin is a city located in Oyo, Nigeria. It is approximately 100 km (62 mi) north of Ibadan. The city was estimated to have a population of 236,000, according to United Nations 2005 estimate, which increased to 362,990 in 2011,[2] and has a total land mass of 2,341 km2 (904 sq mi).[3] Its inhabitants are mostly of Yoruba origin and its ruler is the Aseyin of Iseyin, with the current being Oba Sefiu Oyebola Adeyeri III, Ajirotutu I as at 2024.