Walter Außerdorfer started as a promising alpine skier, winning his first senior race at the age of 15, but his uncle persuaded him to switch to luge. His first appearance at the World Championships was 1959, with his best results at Worlds coming in his last appearance at that event in 1965, with ninth places in singles and doubles. He participated with the Italian national team at the 1964 Innsbruck Winter Games in singles, where he finished 16th, but in doubles, which was his specialty, he had his greatest success winning the bronze medal with Sigisfredo Mair. Even though they were trailing the third-placed German team after the first run, they managed to win bronze with an excellent second run. Außerdorfer later ran the Hotel Krone in his native Tiers, where he also acted as local councilor.