Carroll began his pro career while in Australia in 2012. After building a 2–0 record he returned home to Dublin where he began fighting under Paschal "Packie" Collins, out of Celtic Warrior Gym, Blanchardstown.
Carroll really stepped into the limelight when he accepted the invitation and became Prizefighter champion in December. The Dubliner was a relative unknown to British audiences when he defied the odds to defeat Stephen Foster, Gary Buckland, and Michael Devine to take the lightweight title. Carroll subsequently signed a promotional deal with Eddie Hearn and Matchroom Sport. *