In 1983 Leonhard became German student champion in special jumping before he became German youth champion in 1984. On December 30, 1985 he made his debut in the ski jumping World Cup in Oberstdorf . At the Junior World Championships in 1986 in Lake Placid , Leonhard won the gold medal with the team from the normal hill, before winning the silver medal in Asiago a year later . On December 3, 1989 he was able to win two World Cup points for the first time in Thunder Bay with the 14th place. A week later he was able to win another World Cup point in Lake Placid and with these three points ended the 1989/90 season in 52nd place in the overall World Cup standings. In 1991 Leonhart ended his active ski jumping career after he could no longer achieve any top placements.