Born on October 15, 1991 in County Cork, Ireland, Paul O’Brien rode in point-to-points in his native country for a few years before moving across the Irish Sea to become conditional jockey to Donald McCain, in Cholmondeley, Cheshire, in February 2012. He rode his first winner under Rules, Mulligan’s Man, trained by McCain, in a novices’ hurdle at Perth on September 26, 2012. Thereafter, his career has been one of steady progress through the ranks.
After 18 months with McCain, which yielded just two winners, O’Brien was offered the job as conditional jockey to Rebecca Curtis in Newport, Pembrokeshire, for whom he had previously ridden out while still an amateur in Ireland. He rode seven winners in 2013/14, all for Curtis, before moving on to Colin Tizzard in Milborne Port, Dorset. It was not until 2017/18, though, that O’Brien broke into double figures for the season, by which time he had moved on again, to Charlie Longsdon in Chipping Norton, Oxfordshire.
After riding 14 winners in 2017/18, O’Brien rode 10 more in 2018/19, including his first Graded winner, Castafiore, trained by Longsdon, in the Grade 2 Altcar Novices’ Chase at Haydock on January 19, 2019, and 10 more in 2019/20. He finally rode out his claim on Takeit Easy, trained by Pam Sly, in a conditional jockeys’ handicap hurdle at Wetherby on October 13, 2021. Afterwards, he said, “I wouldn’t say it was on my mind but I was aware that I only had one left.”
The following year, 2022, O’Brien joined forces with Harry Derham – then in his first season in the training ranks – in Upper Lambourn, Berkshire and, as stable jockey, has continued to flourish ever since. Early on, Derham said of him, “For a trainer just starting out to have someone to help school and work the horses on a regular basis has been fantastic. He now knows all of my horses inside out and in return for him supporting me I am going to do the same to him on the track.”
In 2024/25, O’Brien rode a career-best 52 winners and, on November 15, 2025, recorded his second Grade 2 victory on One Horse Town, trained by Derham, in the Prestbury Novices’ Hurdle at Cheltenham. Interviewed in April 2025, he included Givemefive, on whom he won the Masterton Holdings Hurdle at Cheltenham on October 26, 2024 – thereby giving Derham his first winner at Prestbury Park – and Washington, on whom he won a valuable handicap hurdle at Fairyhouse on December 1, 2024, among his career highlights so far.