Connacht Griffin first played professionally for the Irish provincial team
Connacht, based in his hometown of Galway and was first called into the squad against
Olympus Madrid. Griffin scored a try on his first competitive start for the province in their defeat to the
Llanelli Scarlets on 25 April 2010. He played seven times in
2010–11 Celtic League, scoring one try, Connacht played in the
Heineken Cup for the first time in the
2011–12 competition, with Griffin playing in three of the province's six games. He started in the away match with
Harlequins, the home match with
Toulouse and the away match against
Gloucester. Connacht featured in the top European competition again that season, with Griffin playing four times in the
2012–13 Heineken Cup. In the 2013–14 season, he played 19 times in
the league and four times in the
Heineken Cup. it was announced in February 2014 that Griffin had signed for
English Premiership side
London Irish and would leave at the end of the season. He made a total of 71 appearances in his first spell with Connacht. He made his first appearance on 19 October 2014 when he started against Italian side
Rovigo Delta in the
2014–15 Challenge Cup, and scored a try on his debut as Irish won 70–14. He made his
Premiership debut on 15 November 2014 against
Sale Sharks. Griffin made a total of 12 Premiership appearances and five Challenge Cup appearances in his first season. He also started in all four of London Irish's games in the
2014–15 Anglo-Welsh Cup. In his second season, Griffin struggled for game time due to injury. He appeared in three games in the
2015–16 Premiership, Griffin left the club at the conclusion of his contract, having played 24 times for the side in his two seasons.
Return to Connacht It was announced in December 2015 that Griffin had agreed to rejoin Connacht on a two-year deal ahead of the
2016–17 season. He made his return debut in the opening game of the season against
Glasgow Warriors. He made just seven appearances in his first season back with the team, all of them coming in the league. ==International representation==