Peter Müller joined the Swiss national alpine skiing team in the late 1970s and competed in his first World Cup events in 1977. He participated in his first World Championship in 1978, where he was fifth in the downhill, which was the same year that he achieved his first podium finishes at the World Cup (second twice in the downhill). His first victory in the event came a few months later, in February 1979, and he had a strong debut at the Winter Olympics in 1980, finishing fourth in the downhill only 0.13 seconds behind Canadian bronze medalist Steve Podborski. He would make up for it in the next two editions, however, earning silver in the downhill in 1984 and 1988, and picking up a World Championship title along the way in 1987. In addition to silver medals at the 1985 and 1989 World Championships, he had 51 World Cup podium finishes, 19 of which were victories in the downhill, and three and two of which were first-place finishes in the combined and Super G respectively. He was the World Cup leader in the downhill in 1979, 1980, and 1982 (tied with Podborski). His last podium finishes came in 1988, but he remained active on the international scene until his 1992 retirement. He later took up, and found great success in, the sport of orienteering.