In 1999 Kavanaugh had his first official taste of jiu-jitsu at a workshop in London, England, with John Machado. Kavanaugh was grappling for a while by then, but never with proper instruction, and the finner details of a highly-skilled black belt are said to have fully captivated John. During the following months, the young Irishman saved every penny he could get a hold on, and by early 2001 he had gathered enough to visit the Machado school in California, where he stayed for a few weeks. It is assumed that it was ait this point that John earned his blue belt, though this could not be 100% verified by BJJ Heroes.

Later, in November 2001, Kavanaugh fought for a South African MMA promotion (Pride and Honor), outside Johannesburg. He lost his fight, but at the event’s after-fight, John met BJJ black belt Matt Thornton, who was there cornering a fighter. The two connected and trained the following day. Kavanaugh kept in touch with the American grappling coach from then on, visiting his gym Straight Blast Gym in Oregon, USA, while also bringing Thornton to Ireland for a few workshops during the following years. This partnership would lead John to open an affiliate academy to Thornton’s team, Straight Blast Gym – Ireland (SBG).

In late February 2007, during one of Thornton’s visits to Kavanaugh’s SBG academy in Dublin, Matt promoted John to BJJ black belt, this way making Kavanaugh the first person to reach the rank in the Republic of Ireland.

Throughout his career, John has been involved not only with SBG but also with the foundation of the Irish BJJ Association and the Irish MMA Associaton. His many achievements led Fighters Only magazine to award Kavanaugh the Coach Of The Year title in 2017, at the World MMA Awards.