Walchhofer debuted in the Alpine Ski World Cup in 1999. During the same season he also won the Europe Cup. His first World Cup victory came in the Combined of Kitzbühel in 2003.
During St. Moritz -Switzerland- World Championship in 2003, he gained the gold medal in the Downhill event. In 2005 edition he won the bronze in the same discipline, and the silver in the Super Giant.
He won the Downhill World Cup in seasons 2004-2005, 2005-2006 and 2008-2009.
In Turin, at the 2006 Olympic Games, he got the second position in Downhill. Walchhofer, with his bib number 10, kept the first position for a long time, but in the end got passed by the French skier Antoine Deneriaz for 0.72 seconds.
During the 2009/10 World Cup he stepped on the podium four times, in the Super G and Downhill events.
Winter Olympic Games
- 1 silver medal (Downhill in 2006)
- 1 gold medal (Downhill in 2003)
- 2 silver medals (SuperGiant and team competition in 2005)
- 1 bronze medal (Downhill in 2005)
- 3 Downhill World Cups (2005, 2006, 2009)
- Best placement in the overall ranking: 4° in 2005