With only three caps, the Blackburn Rovers defender is the least experienced player in the panel, but Keane does not believe that it is a hindrance to the 24-year-old.
"I think so, sometimes you have to throw young players in. That’s part of football," Keane told reporters. "When you look at his short career so far, the fact is that he has gone out and played games regularly at club level. That was a huge boost for him."
The former Everton defender scored four goals in 41 league appearances for Rovers in the Championship last season and Keane has been impressed by his physicality
"[He's] a big strong boy and has got lots and lots to learn about the game. He is far from the finished article but he has given himself a chance," added the former Manchester United captain.
"A few months ago he would have been touch and go to make the squad. He has impressed everyone in his training and in the games he has played.
"And on top of getting in the squad, I think he has a great chance of making the starting XI. He has been a big plus this last few months and we are delighted to have him on board.
"He is very good, obviously, in both boxes, which is pretty important in a centre half."
Ireland get their Euro 2016 campaign off to a start when they face Sweden at the Stade de France on June 13.