- First competed in the Olympics at the 1972 Games in Munich.
- Won two medals at the 1979 Pan American Games, a silver in team jumping and a bronze in individual jumping.
- Made Member of the Order of Canada in 1986. Inducted into the Canadian Sports Hall of Fame in 1996 with his horse, Big Ben.
- Won a silver medal at the 2008 Olympics in Beijing in the team jumping event.
- Set a world record for number of Olympic starts in 2012 with 10, only missing the 1980 Olympics, which were boycotted by Canada.
- Competes alongside son Jonathan and daughter Amy in what they dub "Team Millar."
- Amy Millar — Daughter
- Lynn Millar — Wife
- Jonathan Millar — Son