The Roman Catholic Diocese of Issele-Uku (Latin: Isseleukuan(us)) is a diocese located in the city of Issele-Uku, Delta State in the Ecclesiastical province of the Roman Catholic Archdiocese of Benin City, Edo State, Nigeria. It lies on the west bank of the Niger River between Benin City to the west and Onitsha to the east. The diocese comprises six local government areas in the northern portion of Delta State. The Archdiocese of Onitsha borders it on the east and the Archdiocese of Benin City borders it on the west. The Diocese of Uromi is to its north and the Diocese of Warri borders it on the south.