Jouko Karjalainen made his international début at the 1978 World Championships, where he was eighth in the Nordic combined. Next Karjalainen competed at the 1980 Winter Olympics, where he won a silver medal and he repeated this feat at the next Olympic Winter Games. In 1981 Karjalainen won his only victory at the Holmenkollen Ski Festival and in 1982 Karjalainen won his first World Championships medal, a silver in the team event, while placing fourth individually. Karjalainen won three more medals at the World Championships, silver again in the 1984 team event, and bronzes in both individual and team events in 1985. By profession Karjalainen was a soldier, being a Master Sergeant in the Häme Regiment. He also worked as a coach of the Finnish Nordic combined team from 1998-2002 and 2006-08.