Maria Walliser first competed for Switzerland in alpine skiing at World Cup events in 1980 and earned her two podium finishes, second in the combined and third in the slalom, the following year. She attended her first World Championship in 1982, where she was 12th in the downhill and 11th in the combined, and captured World Cup victories in 1983 by winning three downhill events. She had one more victory in 1984 prior to the Olympics, which she entered as a slight favorite in the downhill. In Sarajevo, however, she came up short of her compatriot Michela Figini’s gold medal-winning time by 0.05 seconds and had to settle for silver, while also failing to complete the giant slalom. Nonetheless she captured the downhill World Cup title that year and followed it up with overall titles in 1986 and 1987. The latter year was arguably the best of her career, as she also won the downhill and Super G events and bronze in the giant slalom at the World Championships. At the 1988 Winter Olympics she was considered a favorite in the downhill and the Super G, but ended up fourth and sixth in those events respectively. She did, however, capture bronze medals in the giant slalom and the combined.
Walliser had one more major victory, in the downhill at the 1989 World Championships, prior to her retirement in 1990. She had 72 podium finishes at the World Cup over her career, 25 of which were victories. Since 2000 she has been president of Die Stiftung Folsäure Offensive Schweiz, a Swiss organization that helps spread information on the dangers of folate deficiency. She also helps runs their vineyard and, in 2012, appeared in commercials to promote Activia.