The Diocese of Sambalpur, formerly called "Gangpur Mission" was started by the Jesuit Fathers in 1908. The Divine Word Fathers took it over in 1948. Today it is one of the suffragans of the Archdiocese of Cuttack - Bhubaneshwar.

The diocese was erected by the Apostolic Constitution dated June 14, 1951 by taking over parts of the Archdioceses of Calcutta, Ranchi and Nagpur. Then it consisted of districts of Sundargarh, Bolangir, Sambalpur and Dhenkanal in the State of Orissa. Bp Herman Westermann, svd, was consecrated on July 29, 1951 as its First Bishop who after 23 years of dedicated service, retired on March 16, 1974.

One of the four districts, Sundargarh was separated from the diocese on July 16, 1979 and the Diocese of Rourkela was created. Its First Bishop Bp Aplhonse Bilung, svd, was ordained on November 3, 1979. Abp Raphael Cheenath, svd, who was residing in Rourkela before the division, shifted his residence to Sambalpur on November 18, 1979. Abp Raphael Cheenath, svd, was transferred to the Archdiocese of Cuttack - Bhubaneshwar in 1985. He was succeeded by Bp Lucas Kerketta, svd, in 1987.

After its division the diocese is bounded on the North by the Diocese of Rourkela and on the South by the Archdiocese of Cuttack - Bhubaneshwar. To the West and the North - West lie the Dioceses of Raipur and Raigarh respectively, while the Diocese of Balasore lies to the East and South - East.