The son of a Swiss professor of drawing, engraving, and enamelling received his artistic training in Paris, where he saw his first successes.
In 1771 he became a pupil of J. M. Vien at the Academy, and in 1780 won the Prix de Rome with his depiction of the 'Rape of the Sabine Women'. As a Swiss citizen, he nonetheless had to finance the trip to Italy himself, though that did not prevent him from staying a long time (1780-1792). In Rome he soon found public acclaim and was awarded a large number of commissions. At the same time, he produced numerous sketches of impressions of the southern landscape and studies of the city's ancient and Baroque works of art. The artist finally adopted a neoclassical idiom with the corresponding subject matter. In 1792 Saint-Ours returned from Rome to his native Geneva, where he worked as a portraitist as well as a history painter.