Playing career Gavin attended
Moyle Park College, where he played for the college team. His performances for
Round Towers caught the eye of the Dublin selectors, making his senior debut in 1993. His subsequent military pilot training with the
Irish Air Corps ruled him out of any involvement with the under-21 side. With Dublin, Gavin won the
1995 All-Ireland Senior Football Championship.
Managerial career In 2009, he coached Dublin to a
Leinster Under 21 Football Championship and progressed to the All-Ireland final where they lost to
Cork. He repeated the Leinster victory in 2010, going one better than the previous year by winning the
All-Ireland Under 21 Football Championship final. His selectors were
Declan Darcy,
Shane O'Hanlon and
Jim Brogan. Gavin was ratified as senior football manager on 1 October 2012, replacing
Pat Gilroy and signing a three-year contract (2013–2015).
Mick Deegan,
Davy Byrne and Declan Darcy were his selectors for 2013. 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. Then he complained that things were "too drawn out". 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. Dublin won the final on 22 September 2013, beating
Mayo by 2–12 to 1–14. In December 2013, Gavin was named the 2013
Philips Sports Manager of the Year. Dublin could not defend that title though in 2014,
Donegal comprehensively defeating Gavin's team by a scoreline of 3–14 (23) 0–17 (17), in an
All-Ireland SFC semi-final on 31 August which went into the record books as
Gavin's only championship defeat as Dublin senior manager. Dublin again beat Kerry, this time by 0–12 to 0–9, in the
2015 All-Ireland Senior Football Championship final, to win a second All-Ireland SFC title in three years. The following year, in September 2016, Mayo held Dublin to a 2–9 to 0–15 draw in the
2016 All-Ireland Senior Football Championship final, but prevailed by a scoreline of 1–15 to 1–14 in the replay in October, winning back-to-back All-Ireland SFC titles, and a third title in four years. In September 2017, he led Dublin to a third consecutive All-Ireland SFC title, his team again defeating Mayo by a scoreline of 1–17 to 1–16. This was Gavin's fourth All-Ireland SFc title as the Dublin manager. In 2018, he led Dublin to a fourth consecutive All-Ireland SFC title, Dublin defeating
Tyrone by a scoreline of 2–17 to 1–14. This was Gavin's fifth All-Ireland SFC title as Dublin manager. In
2019, he led Dublin to an unprecedented fifth consecutive All-Ireland SFC title, Dublin defeating Kerry by a scoreline of 1–18 to 0–15 in the replay, after a drawn game. This was Gavin's sixth and last All-Ireland SFC title as Dublin manager. Under Gavin's management, the Dublin senior football team established a new record for most National League and Championship games unbeaten. When defeating
Roscommon by a scoreline of 2–29 to 0–14 in a
March 2017 National League game at Croke Park, Dublin set a new record of playing 35 games in league and championship without defeat. They extended this unbeaten run to 36 games a week later with a win away to
Monaghan in the National League. That 36-game unbeaten run came to an end on 10 April 2017 in the National League final, which Dublin lost lost by a single point (0–20 to 1–16) to Kerry, the previous holder of that record, which had stood for 84 years. Gavin announced his decision to end his time as manager on 30 November 2019. He informed his players at Innisfails in
Balgriffin on a Saturday evening that month. Assessment of Gavin's term as Dublin manager has seen him described as one of the greatest managers in Gaelic football history. ==Military career==