Kavanagh turned professional in 2009. He subsequently moved to
Los Angeles where he would train under
Freddie Roach at the Wild Card Gym, and frequently spar with fighters such as
Manny Pacquiao. Kavanagh won on his professional debut on a card with title contenders
Victor Ortiz and
Amir Khan on 15 May 2010. Kavanagh was named Irish Boxing's Prospect of the Year at the National Boxing Awards in February 2011, beating off competition from Belfast
flyweight Jamie Conlan in the process. On 14 July 2012, he beat Paul Valarde in a unanimous decision. On 3 November 2012, he defeated Ramon Valadez (11–3, 6 KOs) in an 8-round slugfest at the
Phoenix Club in
Anaheim, California, with some boxing pundits stating that round 3 was a "Round of the year" contender. In June 2013, it was confirmed that Kavanagh had left Freddie Roach and the Wild Card Gym. "Freddie can’t give me all his time. I need, at this point of my career, to be with someone who can", Kavanagh said. "Freddie hadn’t been with me for the last six fights. I needed to shake things up." After voicing his concerns to
Golden Boy, they put him in touch with
Joel Díaz, who Kavanagh began training with instead. In February 2016, Kavanagh was scheduled to fight Portuguese boxer Antonio Joao Benito at the
National Stadium in Ireland. During the weigh-in for the match, five gunmen stormed the room, killed Dublin gangster David Byrne and injured two others. The
Continuity IRA claimed responsibility for the attack. Later that day, the
Boxing Union of Ireland announced that the fight would be cancelled. ==Personal life==