The Matchroom Boxing chief raised eyebrows at a press conference last week as he told Allen in front of the gathered audience his next fight would be his final opportunity under the Hearn banner.
Allen will face a rematch with Lenroy Thomas for the Commonwealth heavyweight title on March 3 in Sheffield after failing to perform at his best in their first meeting for the crown last May at Bramall Lane.
After piling the pressure on Allen, Hearn told the Free Press there is no point sugarcoating the situation facing the man known as the White Rhino.
“I love Dave Allen but you can only give him so many chances and this is his last chance,” Hearn said.
“There’s a lot of pressure but I believe he’s got to go in there with the desperation to win.
“In the last fight he went in there unfit and I think he let himself down at Bramall Lane.
“I wouldn’t like him to live with that so I want to give him another chance to overcome that.
“If he can’t do it, he’s just not good enough.
“But I believe he should beat Lenroy Thomas.
“If he does, he becomes Commonwealth champion, and everyone will be very happy.”
On what effect he thinks putting pressure on Allen will have, Hearn said: “It might work either way. It’s relevant.
“If it doesn’t then tough luck.
“There is pressure because if he doesn’t do it now then he’ll never do it. He’s got to get it over the line.”
Hearn embarked on Operation White Rhino last year, aiming to capitalise on Allen’s internet popularity and undoubted charisma plus his natural ability as a fighter.
But Allen has yet to fully show his potential in the ring – typified by his poor conditioning and performance in the first Thomas bout.
And Hearn insists it is now or never.
“He’s starting to build that fanbase where if he can get the win and actually show he can fight, then he could be a major player in the division,” he said.
“But he’s got to beat Lenroy. Lenroy Thomas is good but Dave Allen should be beating guys like that if he is any good himself.
“We’ll find out.”