The defender had been struggling with a back problem and was rated doubtful to feature in the clash against Celtic on Sunday. Boss Pat Fenlon confirmed that McPake had now lost his battle to be involved in the end of season showpiece.
"James is not going to make it to be honest. We made that decision today. He hasn't trained today. It's unfortunate for him, he's a big player for us and the captain of the team, but he won't be available," he said.
"In the position he is playing in, it's too much of a risk for everybody - for James and for us as well. I think it was wise to make the decision early.
"He hasn't done enough training wise. We were trying to give him a chance to get himself right but it was clear yesterday and today that that's not going to happen.
"It's a big blow. Losing players and losing your captain is a big blow but we've got players there. We will just have to get on with it.
"These things happen in football. It's more of a blow for James, it's hard for him to take, to miss the cup final.
"We've got to make sure that we give him a chance to enjoy it after if we can."
Teenager Jordon Forster could continue in central defence after deputising for McPake in the last three games, which have all resulted in Hibs victories.
The 19-year-old has lined up alongside Paul Hanlon although Tim Clancy could come back after stepping up training following a month out with a groin problem.
- Sports & Recreation
- Pat Fenlon