Floyd Mayweather Jr will fight Manny Pacquiao in Las Vegas in what's expected to become boxing's richest ever bout.
Mayweather announced the welterweight fight by posting a photograph of a signed contract online.
The 37-year-old fighter is expected to earn more than $120m (£77m) from the bout, while Pacquiao's split of the purse is likely to be around $80m (£52m).
The fight has been in the making for the past five years and follows lengthy negotiations over television rights. Rival networks reportedly thrashed out the terms for televising the fight earlier this month.
Additional stumbling blocks have been overcome in recent weeks, with both camps reaching an agreement on drug testing and both men able to wear their own gloves. No rematch clause has been included.
Pacquiao had spoken openly about his desire to reach a deal, but there had been silence from Mayweather until he announced the news via social media.
"What the world has been waiting for has arrived," said American Mayweather on the social networking website Shots.
"Mayweather vs. Pacquiao on May 2, 2015 is a done deal.
"I promised the fans we would get this done, and we did. We will make history on May 2nd. Don't miss it! This is the signed contract from both fighters.
"Giving the fans what they want to see is always my main focus. This will be the biggest event in the history of the sport. Boxing fans and sports fans around the world will witness greatness on May 2.
"I am the best ever, TBE, and this fight will be another opportunity to showcase my skills and do what I do best, which is win. Manny is going to try to do what 47 before him failed to do, but he won't be successful. He will be number 48."
The 37-year-old American, nicknamed "Money", is unbeaten in 47 fights with 26 knockouts, but Pacquiao is considered the biggest threat to his status as the best pound-for-pound fighter on the planet.
Pacquiao was sleeping in the Philippines when the fight was announced, but his camp issued a statement saying the fans deserve the long-awaited fight.
"Pac Man" suffered back-to-back defeats in 2012, the second a shocking loss to Juan Manuel Marquez, but he repaired his reputation with three straight victories.
"It is an honour to be part of this historic event," said Pacquiao. "I dedicate this fight to all the fans who willed this fight to happen and, as always, to bring glory to the Philippines and my fellow Filipinos around the world."
Fight experts have been divided in their predictions for this eagerly anticipated encounter, with some favouring Pacquiao's all-action fighting style, while others back Mayweather to prevail with his slick counter punching.