MacGeorge was born in Castle Douglas in Dumfries and Galloway. In 1880 he attended the Trustees' Academy in Edinburgh and was a prize-winning student. In 1883 MacGeorge and his friend and fellow student E.A. Hornel enrolled in the Académie Royale des Beaux Arts in Antwerp, and again MacGeorge excelled. There he studied under the Belgian painter Charles Verlat. On his return to Edinburgh he started to work professionally and also had a studio in Kirkcudbright that he would use in the summer. In 1929 he married the watercolour painter Mabel Victoria Elliot who was the widow of the artist Hugh Munro, and they settled in Gifford, East Lothian.