The son of ten-time Canadian Olympian, Ian Millar, Jonathon began riding at age eight on the family farm in Perth, Ontario, alongside his younger sister, Amy.  However, it wasn’t until the early 1990s that he developed a serious interest in competing.

Following a successful Young Riders’ career where he helped Canada earn team gold and silver medals respectively at the 1992 and 1993 North American Young Riders’ Championships, Jonathon entered the grand prix ranks the following year.  He made a strong impression, earning a fifth place finish in the 1994 World Equestrian Games selection trials.  That same year, Jonathon made his Nations’ Cup debut riding for Canada at the Washington International Horse Show.

At the end of the 1996 season, Jonathon moved to the Netherlands to train with renowned Dutch Olympian, Emile Hendrix.  Following three years of invaluable European experience, he returned to Canada in time to contest the 2000 Sydney Olympic selection trials and was named a Canadian Olympic Team alternate.  That fall, Jonathon had the unique distinction of riding alongside his father in three prestigious Nations’ Cup events in Calgary, Washington, and Toronto.

In 2018, Jonathon represented Canada in three Nations’ Cup competitions with his top mount, Daveau, including the €250,000 CSIO5* Longines Nations’ Cup in Coapexpan, Mexico, where he jumped double clear to secure a Canadian victory.  His 2019 season is off to a strong start with a second-place finish riding Daveau in the $100,000 RAM Grand Prix at the Caledon Equestrian Park in Palgrave, ON.

Jonathon married Kelly Soleau, a competitive grand prix rider representing the United States, in December of 2015.  Based at Millar Brooke Farm in Perth, Ontario, where they operate a busy training and sales business, the couple competes throughout North America as well as Europe.  In the winter months, they relocate to Wellington, FL, with their horses and clients.