Krieghoff was born in Amsterdam, Netherlands. When Cornelius was a boy, his father returned to Germany and worked for Wilhem Sattler to establish a wallpaper factory. His family was given accommodations in Schloss Mainberg, a 12th-century castle owned by Sattler, situated overlooking the Main River. He was initially taught by his father and then entered the Academy of Fine Arts in Germany about 1830. He moved to New York in 1836, and enlisted in the First Regiment of Artillery in the United States Army in 1837. While in the army, he made sketches of the Second Seminole War. He was discharged from the army in 1840. Together with his wife Émilie Gauthier, he moved to Montreal around 1846. He participated in the Salon de la Société des Artistes de Montréal. While in Montreal, he befriended the Mohawks living on the Kahnawake Indian Reservation and made many sketches of them from which he later produced oil paintings.