O’Hara, who made his debut in 2012 at the age of 16 and can play in either midfield or defence, started 14 times for Killie this season.
The 19-year-old told the club’s website: “I am delighted to have signed on again for the club.
“My goal for 2015/16 is to firmly establish myself in the first team with the hope of helping the club achieve a top-six spot”.
Manager Gary Locke added: “I am really pleased to be keeping our best young talent at the club, it was a coup for us to keep him.
“He is only 19 and has a big future ahead of him. I’m sure he will kick-on and do very well next season.”