[2] Gavin was introduced to Gaelic football by his father, a native of County Clare and former chairman of the local club team in Clondalkin.
He developed his skills in the local street leagues before winning a record six Cumann na mBunscoil medals as a dual player with Clonburris National School.
Gavin attended and represented Moyle Park College, before later enjoying championship successes at underage levels with the Round Towers club.
His parents are both from west County Clare - his father Jim Senior is originally from Cree and his mother Ann (née Vaughan) is from Moy.
[3] His father previously won a county championship with Cooraclare GAA in 1964, and coached neighbourhood teams in the local street leagues at various levels.
[4] Jim represented Clonburris Primary School in Gaelic games, winning six out of six Cumann na mBunscoil finals in Croke Park - three in football and three in hurling.
[11] Gavin was ratified as senior football manager on 1 October 2012, replacing Pat Gilroy and signing a three-year contract (2013–2015).
On 28 April 2013, Dublin won the first of four consecutive National Football League titles a 0–18 to 0–17 win against Tyrone at Croke Park.
[14] He led Dublin to the 2013 All-Ireland Senior Football Championship final, with the team defeating Kerry in the semi-final on a scoreline of 3–18 to 3–11.
Under Gavin's management, the Dublin senior football team established a new record for most National League and Championship games unbeaten.
[26] Gavin is a qualified commercial pilot,[27] and after his retirement as Dublin manager, he started working for the Irish Aviation Authority as a director of people and operations.