The 65-year-old – known in his home country as Captain Canada on account of his lengthy sporting career – made his first appearance in Munich in 1972.
Now he has surpassed the previous record of nine appearances held by Austrian sailor Hubert Raudaschl – only missing the 1980 Moscow Games because of Canada’s boycott.
Millar, a horse trainer and breeder based in Ontario, enjoyed a personal best in the individual round after riding Star Power to ninth place at Greenwich Park. In the team event he helped Canada to fifth spot with teammates Jill Henslewood and Eric Lamaze.
Over the course of his career the elder statesman of equestrian sport has won a record nine medals at eight Pan American Games, including individual gold in 1987 and 1999. He also helped Canada to a team silver in Rio de Janeiro in 2007.
The 10-time Canadian champion made history in the sport when in 1989 he and Big Ben – with which he won a record 40 Grand Prix titles – became the first rider and horse partnership to win back-to-back World Cup finals.
Millar has been a member of every Canadian team at the World Championships since 1972 and anchored the country’s squad riding In Style in Beijing in 2008, where he led the team into a jump-off for gold with the USA, eventually winning silver, his first Olympic medal.
Though most events at the Games are dominated by younger athletes, the very best competitors in equestrian sports are often more mature – a reflection of the unique balance of riding knowledge and technical expertise required to perform at the highest level in equestrianism.
As Millar explained: ‘The age of the top riders tends to be older because it takes a lot of time to be consistent.’
But does that apply to the horses? Star power, a Dutch Gelding, will be 14 by the time Rio 2016 comes around, and Grand Prix jumping horses typically hit their peak between 12 and 15.
Asked after the individual final whether horse and rider had another Games performance in them, Millar told reporters: ‘If Star Power wants to go, which is very likely because he should be the right age, he can’t go without me. So I will go.’
Millar has stated one of his unfulfilled ambitions is to ride at an Olympic Games for Team Canada with his children Jonathon, 38, and Amy, 35, both competitive international showjumpers who have represented their country.
All things being well, Team Millar could well make it to Brazil in 2016 for another family first.