[1] Kelleher was part of the St Michael's side that won the Leinster Senior Cup in 2012,[2] and reached the final in 2013.
[3] After finishing secondary school, Kelleher attended University College Dublin where he studied economics.
[6] In May 2016, it was announced that Kelleher was leaving Leinster to join provincial rivals Connacht,[5] having turned down a senior contract.
[8] He was playing regularly for Connacht until he tore his hamstring against Wasps in December 2016, which severely interrupted his season.
Kelleher also started four of the team's six group games in the Challenge Cup and the quarter-final against Sale Sharks.
[11] On 28 May 2021, it was confirmed that Kelleher travelled to England to sign for Ealing Trailfinders in the RFU Championship from the 2021-22 season.
He made nine appearances and scored three tries in his time with the team, featuring in both the 2014 Under-20 Six Nations and 2014 Junior World Championship.
[14] He was named on the bench for the uncapped match, and played the last five minutes of the game after coming on as a late replacement for Collie O'Shea.