The heavyweight contender is looking to avenge his loss to Povetkin last year as the pair clash this weekend and Hearn is under no illusions about how important the fight is for Whyte's career ambitions.
The promoter told Sky Sports: "(The fight is a) must-win, because Dillian Whyte's aim is to win a world heavyweight championship.
"Dillian Whyte's aim and our aim is to get him in the position to fight for the world heavyweight championship. Without that, I don't think he has any interest, career-wise. That is the ultimate strategy, aim, focus. If he loses against Povetkin, that is out - and it's not just out for six months or a year. That could be out forever."
Whyte was knocked out by Povetkin in their bout last August but Hearn has noticed a difference in the British fighter in the build-up to this fight, describing Whyte as more "spiteful".
Hearn said: "There's a difference with Dillian Whyte in this camp.
"He's gone back to his old ways. He's more spiteful. He's more short and sharp. He wants to do a job on Povetkin. But Povetkin comes into the fight surely with so much confidence. I know he went down twice in the fight, but he did take Whyte clean off his feet and knock him out. He'll be looking to do that again."
He continued: "I think it's going to be a firefight. I think Whyte is going to go out there and try and impose himself on the fight and I think he's going to try and knock out Povetkin in style. I think Povetkin will be thinking, 'one shot, once again it's over'. It's going to be a tremendous fight."