Kitui was made an apostolic prefecture in October 1956 and entrusted to the St Patrick Missionary Society. It became a diocese on November 16, 1963, with William Dunne as the first bishop. The Late Archbishop Lele succeeded Bishop Dunne on February 2, 1996 until he was appointed the Archbishop of Mombasa in 2005. The Diocese was overseen by a Diocesan Administrator until May 2007 when Rt. Rev. Bishop Martin Kivuva was appointed as the Apostolic Administrator. In 2008, Rt. Rev. Anthony Muheria was appointed the Bishop of Kitui Diocese and installed on 10 August 2008. following the retirement of Archbishop Kairo, Bishop Muheria was appointed as the Archbishop of Nyeri Archdiocese in April 2017 and installed on June 17, 2017 at Christ the King Major Seminary Nyeri. For now he is the Apostolic Administrator to Kitui Diocese.
Catholic Diocese of Kitui is found in the ecclesiastical region of Kenya and it is within the Nairobi metropolitan. It covers the whole Kitui County which is comprised of the following districts: Kitui West, Kitui Central, Lower Yatta, Nzambani, Mutitu, Mwingi Central, Mwingi West, Mwingi East, Kyuso, Mutomo, Mumoni, Tseikuru, Katulani, Mwingi West, Matinyani, Kisasi and Ikutha. It is an arid and semi-arid area of approximately 30,496.4 sq. Kms in Eastern Kenya, with a population of around 1,012,709 people according to 2009 census statistics. The Diocese has over 240,000 baptized Catholics.
The first Missionaries to evangelize in Kitui were Holy Ghost Fathers from Kabaa (Machakos) in early 1930s. Also, by the time the Holy Ghost Fathers were introducing Christianity in Kitui, the Consolata Missionaries from Meru were evangelizing in the northern region of Kitui (now Kimangau). The first Mission house was built in 1945 at Mutune. The first Diocesan Priests in the Diocese were Frs. Peter Muema and the Late Boniface Lele, who were ordained in 1974. The first nun to profess was Sr. Teresia Muli (Assumption Sisters of Nairobi) from Boma parish.
The Diocese consists of four Deaneries: Northern Deanery with 10 Parishes, Central Deanery with 8 Parishes, and Southern Deanery with 5 Parishes and Eastern Deanery with 4 parishes. In 1989 there were 16 Diocesan priests and their numbers grew to 30 in 1999. Currently there are 82 Diocesan priests. There are also 12 congregations of Religious men and women serving in the Diocese; with Daughters of Jesus the Good Shepherd (DOJGS) as a Diocesan congregation.