The bout, originally scheduled for the previous day, had been in serious doubt when the New Jersey Casino Control Commission was asked by regulators to ban the promoters, New Contenders, from staging the bout because of alleged ties to organised crime.
Leonard, 40, who has world titles at five different weights, will be fighting for the first time in just under six years.
Joe Calzaghe has vacated the British middleweight title to concentrate all his efforts on gaining a world championship title chance. The 24-year- old Welshman will also bypass a European title offer to go "for bigger things". His promoter, Frank Warren, believes he will be able to secure his fighter a bout with the World Boxing Council champion, Robin Reid, or the World Boxing Organisation champion, Steve Collins, before the end of the year.
Calzaghe, who won three ABA titles, has a 100 per cent professional record, with all but one of his 19 victories coming inside the distance. His next fight is in Bristol next Tuesday against Spain's Jose Bayon.