The agreement ends a wild day of negotiations in which Golden Boy Promotions CEO Oscar De La Hoya initially told ESPN there would be no fight, only to turn around a short time later and announce the fight, in fact, will take place.
Saul "Canelo" Alvarez will fight WBA and WBC world middleweight champion Gennady Golovkin in a rematch on 15 September, says the Mexican's promoter.
Alvarez has maintained his innocence throughout and has even reportedly signed up for complete Voluntary Anti-Doping Agency (VADA) testing to prove it.
The two fighters had been due to fight each other in Las Vegas on May 5 before the middleweight bout was cancelled after Alvarez failed two drug tests.
Golovkin was the holder of three of the major world titles but was recently stripped of the IBF belt after declining to agree to fight mandatory challenger Sergey Derevyanchenko. Alvarez, meanwhile, was expected to seek out top contender Daniel Jacobs, who fought to a close decision loss against Golovkin in 2017, according to Golden Boy. Most boxing experts believe Golovkin won the first fight.
"It's a much bigger fight with all the controversy that has gone on and no love lost between the guys", Loeffler said.
While the proposition of a rematch was floated immediately after the conclusion of that initial fight, a number of issues delayed the second meeting - most notably, Alvarez testing positive for a banned substance in March. "Canelo is very edgy, so I think that's going to get things heated up".