In a land area of 46,021 square kilometers, the diocesan territory covers three sub-divisions of Darjeeling district of West Bengal: Darjeeling, Kurseong and Kalimpong, besides the state of Sikkim and Bhutan.
The diocese is located in the sub-Himalayan mountainous region. The area is the foothill of the Himalayas. Sikkim is the highest Indian region.
The population is 1,470,000 at the end of 2016.
The languages spoken in the diocesan territory are Hindi, Nepali, Bengali, Bhutanese (Dzongksha), Lepcha, Sikkimese, Tibetan, and English.
The Church first came to Darjeeling with the arrival of the Irish Loreto Sisters in 1846 soon after opening the hill station of Darjeeling. The area was then under Patna diocese and was staffed mostly by Italian Capuchins. In 1886, with the establishment of Calcutta archdiocese, the areas of Darjeeling, Kurseong and Siliguri and the state of Sikkim were transferred to Calcutta archdiocese and were cared by the Belgian Jesuits. St. Mary's Theologate at Kurseong, which started in 1889, contributed significantly to the expansion. In 1947, the Jesuits of Upper Canada province came to assist the Belgian fathers. Gradually, they took over and in 1956 it became an independent Jesuit region. On Oct. 14, 1997, the region became a full-fledged Darjeeling Jesuit province. The work in Kalimpong started in 1883, when the fathers of the Foreign Mission of Paris settled down in Pedong with the hope of getting into Tibet. Father A. Desgodins, the founder of Pedong, was a pioneer missionary and a scholar.
In 1929 this area was separated from Tibet and erected as an independent mission within the ecclesial province of Calcutta. In 1931 Sikkim was added to it and the prefecture apostolic of Kalimpong-Sikkim came into existence, with Msgr Jules Douenels as its first prefect apostolic. In 1935 the French fathers handed over the area to the Canons Regular of St. Augustine of St. Maurice, Switzerland, and in 1937 Msgr. A. Gainer was appointed its new prefect apostolic. After 25 years, he handed the territory over to Bishop Eric Benjamin, who became the first bishop of the newly erected Darjeeling diocese. Darjeeling diocese was erected on Nov. 25, 1962.
The kingdom of Bhutan was separated from the diocese of Tezpur and included in Darjeeling diocese on Jan. 21, 1975.
The main industries are tea, tourism, fruits and vegetables.