Till 1940, Guntur formed a part of the Diocese of Nellore. On February 23, 1940, the civil district of Guntur was detached from the Diocese of Nellore and constituted into the new Diocese of Guntur with Msgr Thomas Pothacamury as its First Bishop.

The Telugu Catholics date as far back as 1699. During the Carnatic Mission founded by the French Jesuits, there was a large number of Catholics in the Telugu region. With the suppression of the Society of Jesus in 1773, the Paris Mission Society stepped in the field and great progress was made during the time of Bp Bonnand. Later in 1834, the Telugu districts were attached to the Vicariate of Madras which was first manned by the Irish Priests from Maynooth and All Hallows and next by the Mill Hill Fathers till the constitution of the diocese in 1940, when it was entrusted to the indigenous Diocesan Clergy.

The Diocese of Guntur originally corresponded to the civil district of Guntur. In 1970, when Prakasam district was formed some taluks of Guntur district were taken over in the new district. Hence in 1977, by a decree of "Propoganda Fide" all the taluks in Prakasam district were handed over to the Diocese of Nellore except Addanki Taluk, which belongs to the Diocese of Guntur.