The first Catholic priests ever to come to Assam were Fr.Cacella S.J. and Fr. Cabral S.J. They were on their way to Tibet, in the year 1626. After 1826 when Assam became part of the British Empire, the growth of Tea plantations brought in Catholic immigrants from Bihar and Bengal. In 1850 Assam was united to Lhasa and Fr. Krick of the Foreign Missions of Paris was the first Catholic missionary to set foot in Dibrugarh on 7th September 1851. Frs. Krick and Bourry were killed in February 1854 in Arunachal on their way to Tibet. In 1860 Fr. Mercier is said to have visited Dibrugarh.
In 1870 Assam became part of the Prefecture Apostolic of Krishnagar. Fr. Jacob Broy of the Foreign Missions of Milan was the first resident priest of Assam with headquarters at Guwahati and he looked after Dibrugarh.
In 1889 the Prefecture Apostolic of Assam was created with headquarters in Shillong and Fr. Rudolf Fontaine, a German Salvatorian, opened the Dibrugarh Mission in 1908.
With the outbreak of World War I in 1914, the German Salvatorians were forced to return to their country and the Jesuits of Calcutta looked after Assam. In 1921 the Prefecture of Assam was entrusted to the Salesians of Don Bosco.
It was Fr. Leo Piasecki, sdb., who reopened Dibrugarh Mission at the request of Msgr. Louis Mathias, sdb, on 8th February 1931. From 1934 to 1951 Dibrugarh formed part of the Diocese of Shillong with Msgr.Louis Mathias, sdb, and Msgr.Stephen Ferrando, sdb, as its pastors.
The Diocese of Dibrugarh was carved out from the Diocese of Shillong on 12th July 1951 with Rt.Rev. Orestes Marengo, sdb, as its first Bishop. In 1964 Rt. Rev. Orestes Marengo,sdb, was transferred to the newly erected Diocese of Tezpur. On 6th July 1964 Rt. Rev. Hubert D'Rosario,sdb,was appointed the second Bishop of Dibrugarh. On his transfer to Shillong - Guwahati in 1969 Rt. Rev. Robert Kerketta, sdb, succeeded him on 31st May 1970 as the third pastor of Dibrugarh. When Rt. Rev. Robert Kerketta, sdb, was transferred to Tezpur in December 1980 Rev. Fr. Joseph Variathukala, sdb, was elected as the Vicar Capitular. On 13th July 1981 Pope John Paul II appointed Rt. Rev. Thomas Menamparampil,sdb, as the fourth pastor of Dibrugarh. In 1992 when the Holy See erected the Diocese of Guwahati with Rt. Rev. Thomas Menamparampil, sdb, as its bishop, once again Dibrugarh became vacant and Rev. Fr.Sebastian Karotemprel was elected as the Diocesan Administrator.
Rt. Rev. Joseph Aind, sdb., the first priest of Dibrugarh, was appointed the fifth Bishop of Dibrugarh on the 23rd December 1994. Until 1964 the Diocese of Dibrugarh comprised the present-day Lakhimpur, Tinsukia, Dibrugarh, Sivasagar, Jorhat and Golaghat districts of Assam and Tirap, Changlang, Lohit and Dibang Valley of Arunachal Pradesh as well as the two states of Nagaland and Manipur. In 1964 when the Diocese of Tezpur was erected, Lakhimpur became part of that diocese. In 1973 the Diocese of Kohima-Imphal waserected with the states of Nagaland and Manipur.
The Diocese of Dibrugarh now comprises the civil districts of Tinsukia, Dibrugarh, Sivasagar, Jorhat and Golaghat in Assam and Tirap, Changlang, Lohit, Lower Dibang Valley and Dibang Valley in Arunachal Pradesh.
The diocese celebrated its silver jubilee in 1976 and the then Pronuncio, Most Rev. Luciano Storero was the chief guest. Most Rev. George Baldissery, the Pronuncio, was the chief guest at its golden jubilee celebrations in 2001.