The Church Missionary Society (CMS) which is the missionary society that brought Anglican mission into Igboland believed that Christian mission must be done in the context of a Diocese. The purpose of this paper is to attempt a historical exploration of the history of creation of Anglican Dioceses in Igboland and to critically examine the evangelistic and developmental importance of the system in the Igbo society from inception till the year 2009 when the last set of Anglican Dioceses were created in Igboland sequel to an official embargo placed on creation of Dioceses by the Primate of Church of Nigeria (Anglican Communion) the same year. This study essentially adopted descriptive phenomenology for data collection and analysis. In the process, it was discovered that the first Anglican Diocese in Igboland was created in 1864 and that between 1864 and 2009 about 50 Dioceses were created in Igboland. The analysis also showed that the Anglican Diocesan system did not only constitute a religious factor in the Igbo society but also a factor of human and social development. Keywords: Anglican church, Dioceses, Evangelicalism, Development, Importance