The former Aston Villa youngster, 24, suffered the injury after just 10 minutes of the 3-1 Boxing Day defeat by Sheffield United at Bramall Lane.
O’Hare was playing only his 11th game of the campaign after being sidelined by an early-season hamstring injury.
“It is terrible news. We are devastated for him,” said boss Mark Robins.
“He just lives for football but it is something he is going to have to live without for a little while.”
Robins confirmed that O’Hare will now face an operation and will be out until well into the 2023-24 season.
“He has ruptured his ACL and his knee needs surgery,” added Robins. “You are looking at September at the earliest next year.
“He had a tough start to the campaign with his hamstring and now this happens.
“But we have to keep him around us and get him as fit as we possibly can.”
O’Hare joins fellow midfielder Josh Eccles, defender Kyle McFadzean and striker Matt Godden and Josh Eccles on the Sky Blues’ long-term injury list.
The Sky Blues are 13th in a congested Championship table, just two points shy of a play-off place.
