With Tomi Poikolainen, who he coached after retirement from sports, Kyösti Laasonen is one of most successful of all Finnish archers. He won bronze at the 1972 Olympics and was World individual champion in 1981 and European individual champion in 1968 and 1978, and also was European team champion in 1976. At the World Championships Laasonen won four silvers (1971 and 1973 individual, 1971 and 1981 team), and two team bronzes in 1973 and 1975. At the European Championships, in addition to his three gold medals, he won five silver (team in 1968, 1970, 1978, 1982; and individual in 1971) and two bronze medals (1970 and 1976 individual). Laasonen also won over 20 Finnish titles. After finishing his sporting career, Laasonen has worked as an archery coach.