Augustin Ehrensvärd was a skilled draughtsman and painter like his father. As a young man on a military study trip to Europe, he was briefly taught by the Parisian copperplate engraver Nicolas de Larmessin. Ehrensvärd's engraved portrait of the famous botanist and friend Carl von Linné is the result of these lessons.

in 1747, while planning the Viapor Fortress, Ehrensvärd made a reconnaissance expedition to southern Finland and wrote a two-volume memoir, illustrated with drawings and watercolours, of what he saw. The small-scale, sparse and beautiful views of nature depicted in the document are the first significant body of Finnish landscape photography. Landscape is also an integral part of many of his pictures of the growing buildings of Viapora. Ehrensvärd also made oil paintings, although only a few of the more elaborate Viapora views are known.