The diocese was established on 19 July 1901 as the
Apostolic Prefecture of Ghardaïa () on territory split off from the then
Apostolic Vicariate of Sahara and Sudan (now the
Archdiocese of Bamako in present
Mali), also a pre-diocesan missionary jurisdiction. It was renamed on 10 January 1921 to the Apostolic Prefecture of Ghardaïa in the Sahara (, .) On 28 April 1942, it lost western territory to establish the then
Apostolic Prefecture of Niamey (now the Archdiocese of Niamey.) The prefecture was promoted on 10 June 1948 to an
apostolic vicariate, entitled to a
titular bishop. On 5 July 1954, it lost western territory again to establish the then
Apostolic Prefecture of Spanish Sahara and Ifni (now named the Apostolic Prefecture of Western Sahara) The vicariate was promoted on 14 September 1955 to the Diocese of Laghouat. == Statistics ==