Born in Hawick, in the Scottish Borders, on September 28, 1994, Jason Hart began riding out for Mark Johnston in Middleham, North Yorkshire as a 15-year-old, having previously competed in pony racing. He took his first ever ride on Elusive Fame, trained by Johnston, in a handicap at Southwell on February 1, 2011. Elusive Fame finished second, beaten a neck, but that was the closest Hart ever came to riding a winner while apprenticed to Johnston. Over the next three months, he was beaten a further six times on the same horse, including in a selling handicap at Hamilton, before joining Declan Carroll in nearby Malton.
Carroll provided Hart with his first winner under Rules, Spice Bar, in a handicap at Ripon on August 30, 2011. Reflecting on his inugural victory, he said, “I hadn’t been there for long and it was nice for him [Carroll] to put me on something he thought had a really good chance.” Hart rode seven winners in 2011, but increased his seasonal tally to 18 in 2012 and, again, to 51 in 2013, which was sufficient to win the Apprentice Jockeys Championship. Reflecting on his achievement, he said, “I’m really pleased with the way the final week went, because I’ve had four winners, which has pushed me through the half-century, which was a target of mine.”
Hart rode out his claim in 2014 but, on June 26, 2015, his mount, Dark War, fell, fatally, when in the lead in a six-furlong handicap at Doncaster. He ruptured both the anterior cruciate and medial collateral ligaments in his knee and was out of action for seven months. Thus, Hart rode just 23 winners in 2015 and 37 in 2016, although the latter total did include his first Pattern winner, Ridge Ranger, trained by Eric Alston, in the Group 3 Summer Stales at York on July 8, 2016.
Hart rode his first Royal Ascot winner, Highfield Princess, trained by John Quinn, in the Buckingham Palace Stakes on June 17, 2021. That year, he passed the milestone of 100+ winners for the first time. He would subsequently form a profitable association with Highfield Princess, on whom he won the Prix Maurice de Gheest, Nunthorpe Stakes and Flying Five Stakes in 2022 and the Prix de l’Abbaye de Longchamp in 2023.
Hart reached the landmark of 1,000 career winners on Rhapsody, trained by William Haggas, in a fillies’ handicap at York at September 7, 2025. At that point, he said, “Becoming champion jockey is a burning desire, but it’s not easy and everyone else has the same aim. I’ll keep kicking and give it my best shot.”