Alycia Baumgardner and Mikaela Mayer have agreed terms on a super-featherweight unification bout later this year.
Mayer, 31, is the WBO, IBF and Ring magazine champion while Baumgardner, 28, holds the WBC and IBO titles.
Unbeaten Mayer's promoters Top Rank will oversee the event, which is likely to take place in America.
"Mikaela Mayer's prodigious talent is only matched by her tremendous ambition," said Top Rank's Bob Arum.
"She wants the biggest fights, and Alycia Baumgardner is a worthy champion.
"This is a huge event and one of the most anticipated match-ups in women's boxing."
The announcement follows months of back and forth between Mayer and Baumgardner on social media.
Mayer is undefeated in 17 professional fights while Baumgardner, who has only one defeat, pulled off one of the upsets of 2021 when she knocked out Britain's Terri Harper in Sheffield last November to become WBC champion.
The fight joins a growing list of exciting women's bouts projected to take place this year, including an undisputed middleweight meeting between Savannah Marshall and Claressa Shields as well as the highly anticipated rematch between Katie Taylor and Amanda Serrano.