Prior to 1925 the spiritual needs of the Roman Catholic people in the Deer Lake area were looked after from the old established parish of the Sacred Heart at Petries Crossing. The parish at Petries was the only Roman Catholic Parish in Bay of Islands until 1925 when Holy Redeemer Parish was established at Corner Brook with the late Msgr. Walter Brennan being its first Pastor. Deer Lake and an area extending east to Kitty's Brook and north to Bonne Bay then became the responsibility of the newly established parish in Corner Brook.

In 1927 the onerous duties of Msgr. Brennan created in having to cover such a vast mission territory and by a construction boom in Corner Brook were relieved by the ordination and arrival in the diocese in June 1927, of the Rev. Michael Hayes. Shortly after his ordination Father Hayes was assigned to the Deer Lake area while still being assistant to Msgr. Brennan at Corner Brook. Because of the difficulty of giving regular attention to this area from Corner Brook, Father Hayes took up residence at Deer Lake traveling back and forth to Corner Brook as required. Father Hayes is remembered in Deer Lake by the Roman Catholic people as their first resident priest.

Deer Lake continued to be looked after as mission of Corner Brook and in 1932 the people first became acquainted with the Redemptorist Fathers who had been invited by the late Bishop Renouf to take over the fast growing parish of Corner Brook. During the next eleven years the Redemptorist Father were to make frequent pastoral visits here, usually coming for the weekend and staying for two or three days. They were fortunate in securing living accommodations at the Staff House and later on in a small two-room school, which they built. Perhaps the priests who were best know to the people of this area during this time were Fathers MacKelhinney, Fisher and Dwyer.

The Catholic population in this area was slowly but steadily increasing so that in 1943 it became a parish. Its first incumbent being Msgr. Patrick J. Bromley. During the eight years of Msgr. Bromley's pastoral stay a new parish house was built, land was secured for a new church and work began on its concrete basement, which partly was completed before his transfer to Stephenville in 1951. Msgr. Bromley was succeeded by Rev. Walter Brennan, V.G., D.P. who arrived here in May, 1951. A few years after Msgr. Brennan's arrival, Msgr. Bromley's plans for the new church were continued and saw completion in the erection of what is said to be the first prefab building in Newfoundland. This fine church was completed by Msgr. Brennan in 1953 and is till serving the spiritual needs of the parishioners of Deer Lake.

Msgr. Walter Brennan retired in May 1961, and Rev. Joseph Kelly was appointed Parish Priest in June 1961. In June 1961 the missions of Pynn's Brook, Howley, Woody Point, Noffis Point, Parsons Pond and Cow Head were attached to Immaculate Conception Parish. The mission of St. Paul's, Cow Head and Parsons Pond were removed from Deer Lake on January 1, 1971 and attached to Port Saunders. During Father Kelly's term, Immaculate Conception and St. Francis Xavier Schools were built and opened. A new priest's residence was also purchased situated on Nicholsville Road.

Father Kelly served as Parish Priest until September 1974. He was succeeded by Rev. John Peddle as Parish Priest who served here in Deer Lake until 1980 and was succeeded by Rev. Edwin Gale. Father Gale served as Parish Priest until June 1986, followed by Rev. George Smith, who served as Parish Priest until May 199 1. Father Smith was succeeded by Sister Claudette Gallant and Sister Sarah MacPherson of the Sisters of St. Martha of Antigonish as Pastoral Ministers. They served Immaculate Conception Parish until August 1996 and were succeeded by Rev. John Collins as Parish Priest.