He won two medals in the K-4 10000 m event at the ICF Canoe Sprint World Championships with a gold in 1987 and a silver in 1983. Sletsjøe also competed in two Summer Olympics in the K-4 1000 m event. At the 1984 Summer Olympics in Los Angeles, he was eliminated in the semifinals. Four years later in Seoul, Sletsjøe and his teammates made the semifinals, but did not finish. Sletsjøe later served as president of the Norwegian Canoe/ Kayak Federation.