Kenna formed a highly successful partnership at centre back with Alan McNally in a defence that gave up the fourth fewest goals in the 2006 League of Ireland season.
[1] Kenna made 38 competitive appearances and scored 5 goals for Drogheda in 2009 as the Louth club retained their Premier Division status.
[2] Kenna became a fan's favourite at Inchicore and received the St. Patrick's Athletic Supporters Club Player of the Year award in 2010.
Kenna also earned the nickname 'Kennavaro' after brilliant performances similar to famous World Cup winning central defender Fabio Cannavaro.
It was widely speculated that Kenna would join 2010 league winners and Dublin rivals Shamrock Rovers but he stayed loyal to his club and this made him even more of a popular figure with the fans.
He returned from his long injury setback in a 0–0 draw away to Sligo Rovers on 27 July, Kenna wasn't expected to return so early as he was still building up his fitness but Mahon was forced to play him due to players being tired from a tough game against FC Shakhter Karagandy and he lasted the first 68 minutes before being replaced by Brian Shortall.
Indeed, they were correct as Kenna regained his excellent form in defence and the Saints found themselves with 3 clean sheets and just 2 goals conceded after the first 5 games of the 2012 season.
In October 2000, Kenna played for the Republic of Ireland U16s in a qualifying tournament in Riga for the 2001 UEFA European Under-16 Championship where he came up against Andrés Iniesta.