Haye (right) pulled out of a scheduled fight with Wladimir (left) in 2009, citing an injury
WBA heavyweight champion David Haye will fight IBF and WBO champion Wladimir Klitschko in Germany on either 25 June or 2 July.
On Saturday, Klitschko withdrew from his bout against Britain's Dereck Chisora that was set for 30 April.
And Haye told the BBC that an agreement had been struck on Saturday night: "I finally had a contract in front of me and couldn't wait to put pen to paper.
"It's the fight every boxing fan has to see, and every sports fan."
A protracted recovery from a stomach muscle injury was given as the reason for Klitschko cancelling the Chisora fight.
Klitschko's manager, Bernd Boente told German newspaper Welt am Sonntag that the fight against Haye could take place at one of three football stadiums - Dortmund, Gelsenkirchen or Kaiserslautern.
The announcement brings to a conclusion the long-running saga to get the bout staged.
A back injury forced Haye, the WBA champion, to withdraw from a fight with Klitschko in 2009. And talks stalled last December with the two camps wrangling over the details of the contest.
Haye continued: "The fight will be either 25 June or 2 July, either date is fine by me.
"He is ranked by many as the best heavyweight in the world - in front of myself, even though I'm the WBA champion."
On the negotiation process, Haye said: "He wanted all these little things - he's a bit precious, is Wladimir, so I gave him all these little things to make him feel like he'd got a mental edge.
"The terms were right, it's a fair deal - it's a 50-50 split, that's what they wanted and that's what I wanted.
"I'll just make sure the referee can count to 10, then I'm the new unified heavyweight champion of the world.
"Here it is - end of June, beginning of July - let's get ready to rumble."
Haye claimed that he has already begun preparation for the fight.
"I've been training, I've been out in Miami and done two months of hardcore conditioning, ready for the hardcore boxing training," he said.
"I'm firing on all cylinders, I can't wait to get Wladimir in that ring - it's the fight I've wanted for so long."