Korn was born at Uddevalla in Västra Götaland County, Sweden. He was the son of Filip Ludvig Korn (1698-1741) and Maria Elfwing (1708-1742). He first began his career as a decorative painter. He was a student of artist Johan Sevenbom (1721-1784). After further studies he changed to landscape painting in the Rococo style of French artist François Boucher (1703–1770).[1][4]
In 1759, Korn became master of the Stockholm Painting Office (Stockholms målarämbete) and held this position until his death. Korn became a member (agré) at the Swedish Royal Academy of Fine Arts in 1777.[1][5]