George Thomson was born in Towie, Aberdeenshire, Scotland on 2 April 1860. He trained as an architect in Glasgow and from 1882 to 1886 studied at the Royal Academy Schools in London. He first exhibited at the Royal Academy in 1886, and was subsequently a prolific exhibitor at the RA and elsewhere including at Colnaghi & Co. Gallery, the Grosvenor Gallery, Goupil Gallery, International Society of Sculptors, Painters and Gravers, Leicester Gallery, London Salon, New English Art Club, Royal Society of British Artists, Royal Institute of Painters in Water Colours, and Royal Institute of Oil Painters in London; the Walker Art Gallery in Liverpool; Royal Glasgow Institute of the Fine Arts; Royal Birmingham Society of Artists; and at Manchester City Art Gallery. He was elected a member of the New English Art Club and in 1895.
Thomson worked as an art critic for the Pall Mall Gazette and the Westminster Gazette and lectured in perspective at the Slade School of Fine Art, University College, London, from 1895 to 1914. In 1914 he moved to France and settled at Chateau Letoqui, Samer, Pas-de-Calais, France, where he remained for the rest of his life.
Thomson's style as a painter was influenced by the techniques of the Old Masters and he also excelled as a natural painter en plein air. His preference was for architectural subjects. He died in Boulogne, France on 22 March 1939.