He made his first appearance at an international jumping competition on January 6, 1968 at the Four Hills Tournament at Innsbruck's Bergisel . He immediately reached sixth place, but it was to be his only appearance for two years. From 1972 to 1982 he took part in all the jumping competitions on the tour. But he only achieved a podium place once, namely in 1978 a third place in Innsbruck.
At the 1976 Winter Olympics in Innsbruck he reached 14th place on the normal hill and tenth place on the large hill, at the 1980 Games in Lake Placid he surprisingly won the gold medal on the large hill after eighth on the normal hill. It was his first win at an international tournament. Since the Nordic World Ski Championships in 1980 were held as part of the Olympic Games, he was also world champion. In the ski jumping world cup, which was held for the first time in the 1979/80 season, he managed to win another 1980 in Falun. His successes also include four titles at Finnish championships: in 1976, 1977, 1979 and 1980 he won on the normal hill. After the winter of 1981/82, he ended his sports career.
In 1988 he became a member of the Finnish Ski Sports Federation. From 1993 to 2002 he was Vice President. In 1992 he became chairman of the ski jumping and Nordic combined department. In June 2004, after Torbjørn Yggeseth's resignation, he became FIS Chairman of the International Ski Federation in the discipline of ski jumping.
Törmänen died on January 3, 2015 at the age of 60 in a hospital in his hometown of Rovaniemi.