Mullins started his racing career as an apprentice jockey on the flat. His first winner was My Girl Sophie, trained by Jim Bolger, at Leopardstown on 21 May 2008. Two months later he rode a treble at the Galway Racing Festival. He came second and third in the champion apprentice title, but increasing weight led him to switch to racing over jumps.[1] He won his first graded race in October 2012, on Down in New Orleans, trained by his mother, in the Grade 3 PricewaterhouseCoopers Chase at Limerick.[4] In January 2013, he was signed as the retained jockey for owner Barry Connell.[5] His first Grade 1 win was in Connell's colours, riding Mount Benbulben, trained by Gordon Elliott, in the Champion Novice Chase at Punchestown in April 2013.[4] He lost his retainer with Connell after less than two years, and went back to riding as a freelance.[6] He often rides for his uncle, Willie Mullins. Although usually on the second or third string, he has won a number of Grade 1 races, including the 2021 Irish Gold Cup on Kemboy for his uncle.[6][7]
In his first ride in the Aintree Grand National, in 2019, on Up For Review, trained by his uncle, Mullins was brought down at the first fence.[8] His best results in subsequent years were on Meetingofthewaters, also trained by Willie Mullins, who came seventh in 2024 and fifth in 2025.[9] He won the Grand National Hurdle Stakes in 2017, and the Scottish Grand National in 2024.[4]
Having had about forty rides without success for his uncle Willie Mullins at the Cheltenham Festival over the years, his first win came in 2021 when he picked up a spare ride on Flooring Porter in the Stayers' Hurdle for trainer Gavin Cromwell.[10]
