In 1888 he entered Fort Augustus and made his solemn profession on 10 February 1893.

From 1911, he was attached to Ampleforth Abbey and served as curate at St Anne's, Edge Hill.

He later became rector of the church and held office until he was elected Abbot of Fort Augustus on 27 August 1919.

He was appointed the Archbishop of St. Andrews and Edinburgh on 19 July 1929 and consecrated to the Episcopate on 24 September 1929.

David Ogilvy described McDonald as, "a very sweet old man, the nearest thing to an angel I've ever known".