The former Cork City player joined last season but was loaned to St Mirren before making his debut. He returned for the restarted season and made seven appearances in Hull's doomed relegation campaign, five from the start.
The former Republic of Ireland under-21 international has has been on the fringes this season, limited to 10 appearances. His only League One game was as an 89th-minute substitute against Wimbledon on Saturday but he started six matches in the Football League Trophy.
Even so, the Tigers have seen enough to persuade them that they want to keep the 24-year-old.
"He's a player that we feel has a very bright future at this football club and we're really pleased to see another talented young player commit his long-term future to Hull City ” said coach Grant McCann.
The club have the option of a fourth year.
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