Vaillencourt, who made his mark at the Montréal Olympics, was initiated into equestrian sports early on. His father had purchased an equestrian centre in Saint-Barnabé-Sud, a farming community located 70 kilometres from Montréal, and young Vaillancourt began riding ponies, then full-sized horses since the age of eleven.
During his junior years, this obstacle jumping expert represented Canada on numerous occasions in international competitions, notably in Toronto, where he won the Canadian Junior International World Championship at sixteen, becoming the first French Canadian rider on the junior national team.
Unfortunately, when Vaillencourt was seventeen, his father died in an unlucky accident when his mount fell on him during a training session. Rather than giving up equestrian sports after this tragedy, which disrupted his family, Michel persevered in making his father's dream a reality.
In 1975, he joined the Canadian equestrian team for the PAN AMERICAN GAMES in Mexico City. Michel and his horse U.F.O. stood out and helped the Canadian team take home a bronze medal.
Late in the winter of 1975-1976, Pierre Jolicoeur, Michel Vaillencourt's trainer, found him a new partner named Branch County. To everyone's surprise the duo, newly formed only a few weeks earlier, was successful in the Canadian team trials for the Montreal Olympics.
At these Olympics competitions in Bromont, Que., Vaillancourt delivered a solid performance in the individual jumping competition and won the silver medal. At 22, he thus became the youngest rider in obstacle jumping to win an Olympic medal. It also marked the first time a Canadian received an Olympic medal in equestrian sports. Vaillencourt was Québec's only medal winner in the Montréal Games.
In 1979, Michel Vaillancourt was again successful in the Pan American Games in Puerto Rico. On this occasion, his performance with his horse Crimson Tide helped the Canadian team achieve the silver medal.
The following year, although he qualified for the Olympics as did many other Canadian athletes, Vaillencourt was a victim of Canada's boycott of the Moscow Games. However, the Canadian team's gold at the Rotterdam Show Jumping Festival, an alternate competition to the Moscow Games, confirmed the quality of the equestrian team which would have represented Canada in Moscow.
Michel Vaillancourt held the position of chef d'équipe for the Canadian Show Jumping Team from 1994 to 1998. He remained in equestrian circles and became a major designer of obstacle races in North America.
Mounting the Olympic podium, Michel Vaillancourt incited the pride of Canadians, and realized the dream his father had kept alive in him. He was inducted into the QUÉBEC SPORTS HALL OF FAME in 1996 and the Jump Canada Hall of Fame in 2009.