Age: 32 years, 2 months
Nickname: Marty Waters
Place of Birth: Dublin
Height: 183 cm
Kieran started his League of Ireland career at Bray Wanderers in 2007 and made his way up through the ranks of the Co Wicklow club. In 2009 he played with the club's U20 side and in 2011 he won the club's A Championship Player of the Year award.
2011 was also the year that Kieran broke into the first team and he made his league debut in the 4-0 win over Galway United at the Carlisle Grounds on 12 August. He made 6 league appearances towards the end of the season and scored his first senior goal for the Seagulls in the 6-0 win over Galway United on 21 October 2011. The following year Kieran scored eight times in 28 league appearances and in 2013 he added four more league goals in 33 league appearances. On New Years Eve 2013 he left Bray to sign for Trevor Croly at Shamrock Rovers.
In his first season at Rovers, Kieran made twenty-five league appearances, scoring his first goal in a 3-1 win over Bohemians, as Shamrock Rovers finished in fourth place for the 2014 season. He stayed with Rovers for the 2015 season and went on to make twenty-one league appearances, scoring six times in the process, as Shamrock Rovers finished third in the Premier Division. He also played in three of the club's Europa League matches, scoring twice in the 3-0 home win over Luxembourg side Progrés Niederkorn, as Rovers went out to Norwegian side Odds.
Kieran left Shamrock Rovers at the end of the 2015 season and played in a friendly for UCD against Finn Harps in February 2016. He signed for the Students at the beginning of March and made his league bow for them in a 4-1 defeat to eventual champions Limerick. He scored twice in 28 league appearances that season and added five more goals in Cup competition.
In February 2017 it was announced that Kieran had signed for Pat Devlin at Cabinteely. He went on to score 15 league goals for Cabo as well as scoring one in the FAI Cup and at the season's end he was named First Division Player of the Year. Kieran spent five seasons with Cabinteely, leaving in 2022 when the senior side merged with Bray Wanderers, bringing him back to the club where he started his career.