"Verbal agreements [are] in for what should be an explosive matchup," White said of the bout.
Johnson has competed at welterweight, but consistently struggles to make the 170-pound limit. He knocked out Charlie Brenneman in the first round of their nontitle fight on Oct. 1 in Washington. At the prefight weigh-ins, Johnson (10-3) expressed relief after tipping the scale at 171 pounds.
Fighters are allotted an extra pound for nontitle fights. But Johnson is expected to have little difficulty making the 185-pound middleweight limit.
Belfort (20-9) has competed at 205 pounds for the majority of his professional career. The former UFC light heavyweight champion made his middleweight debut in July 2008, while competing in Affliction.
He is 4-1 since leaving the light heavyweight ranks. His lone loss came Feb. 5, when he was knocked out in the first round of a UFC middleweight title bout by champion Anderson Silva.
Aldo and Belfort are natives of Brazil.
Franklin McNeil covers mixed martial arts and boxing for ESPN.com. Follow him on Twitter at www.twitter.com/Franklin_McNeil.