 Kokkonen's best individual finish at the world championships was 5th in the large hill at Lahti in 1978.At the Winter Olympics, his best finish was fifth in the individual normal hill at Lake Placid, New York in 1980.Kokkonen had two individual victories in his career, both in the normal hill in Austria in 1979 as part of the Four Hills Tournament competition for which he emerged as the overall winner.