He played his first senior competitive game for the Kerry county team on 8 March 2009 when he came on as a substitute in the Irish NFL against Derry, and there was speculation that he would be a member of the Kerry squad for the All-Ireland Senior Football Championship. He went on to win an Irish NFL medal when Kerry defeated Derry in the final in Croke Park. As Kerry had a number of injuries meaning that Darragh Ó Sé, Anthony Maher, Séamus Scanlon and Kieran Donaghy were all short of full fitness, Kennelly played in Kerry's first two games of the All-Ireland Senior Football Championship in June. He picked up an injury during the qualifier series but his form continued to improve and after an impressive appearance as a substitute in the All-Ireland quarter-final against Dublin, he broke into the starting team for the semi-final in which Kerry beat Meath. On 20 September 2009 he played the first 50 minutes of the All-Ireland final win against Cork, scoring 2 points and becoming the first person to win an AFL premiership and an All-Ireland Senior Football Championship. After the final Kennelly committed himself to the Kerry football team for the 2010 season, despite speculation that he was returning to Australia.