Though Guwahati is one of the three new dioceses of North East India, it was the first place to be associated with Catholic Church in the region. Two Portuguese Jesuit Fathers reached Hajjo and Guwahati on September 26, 1626 on their way to Tibet from Hooghly. These were the first Fathers to set foot in Assam. In June 1850, three Fathers of the Institute of the Foreign Church Work of Paris reached Guwahati. In 1872, Fr Jacopo Broy of the Institute of Foreign Church Work of Milan took up residence in Guwahati and looked after the entire "Assam Mission" from this central place. In Guwahati he built a brick church in 1883. In February 1890, the German Salvatorian Fathers reached Guwahati. Fr Gallus Schrole and Fr Rudolf Fontaine were the great Fathers of the Assam Valley. By this time, many Catholics from Chota Nagpur came to work in the Tea Gardens of Assam. In 1922, the Salesians of Don Bosco arrived in North East India. From 1923, Fr Piasecki looked after the whole of Assam Valley from Guwahati.

The Diocese of Guwahati was erected on August 16, 1992 carved out from the Diocese of Shillong, Tura and Tezpur. Bishop Thomas

Menamparampil, sdb, who was the Bishop of Dibrugarh, was transferrred to Guwahati to take charge of the new diocese. With a general population of 6.5 million spread out in an area of 18,588.2 sq. km covering five civil districts of Assam: Nagaon, Morigaon, Kamrup, Nalbari and Goalpara, Guwahati diocese has the care of a vast number of tribes and communities like the Assamese, Rabhas, Garos, Karbis, Tiwas, Hajongs, Adibasis, Santals, Bodos, and Nepalese. Guwahati became an Archdiocese and Bishop Thomas Menamparampil was made its first Archbishop on August 1, 1995. The Archdiocese was bifurcated and the new Diocese of Bongaigaon was erected on August 20, 2000.