Aloys Bigirumwami was born into a Tutsi family on 22 December 1904 in Zaza, Rwanda, and baptized on Christmas Day.

[2] His father, Joseph Rukamba, was one of the first Christians of the Catholic mission that had been founded at Zaza in 1900, baptized on Christmas 1903.

[1] He entered the Major Seminary of Kabgayi in 1921, where he studied under Bishop John Joseph Hirth, founder of the church of Rwanda.

On 14 February 1952 Pope Pius XII appointed Bigirumwami the first vicar apostolic of Nyundo,[4] and titular Bishop of Garriana.

[3] He was ordained bishop at Kabgayi during the feast of Pentecost, on 1 June 1952, in a ceremony attended by many church and civil leaders and by a huge crowd of Christians.

Bigirumwami rejected the existence of a conflict between the two populations,[5] The bishop also believed that the conversion of the pagans within his jurisdiction could be achieved with a large number of priests.

On 10 November 1959 Bigirumwami was appointed Bishop of Nyundo, Rwanda, holding that position until he retired after twenty-one years of service, five days before his sixty-ninth birthday, on 17 December 1973.

However, he gradually came to appreciate the values incorporated in traditional beliefs, and came to think that the church should not destroy local cultures, but should use them as a vehicle for its message.