Born in Downpatrick, County Down, Northern Ireland, Caoilin Quinn started pony racing while still at primary school and during secondary school rode out for local trainer Brian Hamilton, in nearby Ballynoe, at weekends and during school holidays. On leaving school, he joined Warren Greatrex in Upper Lambourn, Berkshire as an a amateur rider and duly rode his first winner, Sarim, trained by Greatrex, in an amateur riders’ handicap on the Flat at Kempton on November 5, 2019, on his first ever racecourse ride.
After a handful of rides in point-to-points, the first of which was Bulfin Island, trained by Roger Varnham, in a restricted point-to-point at Cocklebarrow, Gloucestershire on January 26, 2020, Quinn became conditional jockey to Greatrex. He was immediately successful in that role, too, riding a winner on his first ride, Bill Baxter, in a National Hunt Flat Race at Fakenham on January 4, 2021.
Early the following year, Quinn joined Gary Moore – who, since 2024, has held a joint training licence with his son, Josh – at Lower Beeding, West Sussex as conditional jockey and has remained at the yard ever since. In 2022/23, he broke into double figures for the first time, finishing the season with 25 winners. In 2023/24, he increased his seasonal tally to 28 winners, including Botox Has in the West Yorkshire Hurdle at Wetherby on November 4, 2023, Salver in the Finale Juvenile Hurdle at Chepstow on December 27, 2023 and Nassalam in the Welsh Grand National later on the same day. Botox Has was, in fact, his first Grade 2 winner and prevailed under joint top weight of 11st 6lb despite Quinn being unable to claim his 5lb weight allowance. He said, “He’s unbelievable. I’m speechless to be honest.”
On November 15, 2024, Quinn rode out his claim on Icare Grandchamp, trained by Gary and Josh Moore, in a handicap chase at Southwell. He was, in fact, completing a double on the day for his yard and said afterwards, “I’m over the moon, and huge thanks must go to Gary and Josh as they have made it happen and have been very supportive.” The 2024/25 season, as a whole, yielded 29 winners and, on September 11, 2025, Quinn won the Jump Jockeys Derby at Epsom on Give It To Me OJ, trained by Gary and Josh Moore. “This Flat stuff is easy, isn’t it?!” he quipped afterwards, adding, “It was brilliant riding around here. I grew up watching the Derby and big races around here, so it was a privilege to get to ride around the track.”