Three-weight world boxing champion Claressa Shields will move into mixed martial arts and wants to make history by holding titles in both sports at once.
Double Olympic champion Shields, 25, who has won all 10 of her professional bouts, will continue to box.
"I want to go where no-one has gone and hold championships in both boxing and MMA at the same time," Shields said.
She said she wanted to match the achievements of Bo Jackson and Deion Sanders, who both excelled in two sports - baseball and American football. Jackson is the only professional athlete to be named an All-Star in both sports, while Sanders is the only person to have played in a Super Bowl and a World Series.
"Since turning pro, it has been my goal to be the GWOAT (greatest woman of all time) and to be a two-sport star like Bo Jackson and Deion Sanders," Shields said.
"What drew me to the PFL is that it is definitely a fighter-first organisation, and I can't wait to be a part of that."
Shields, who won middleweight gold at London 2012 and Rio 2016, will compete in a series of 'special attraction' fights in 2021, with a view to enter the league for the 2022 season.
The USA-based PFL's MMA format sees fighters compete in a regular season, play-offs, and a championship for a $1m prize.
Fellow two-time Olympic champion and compatriot Kayla Harrison, who won gold in judo in 2012 and 2016, also competes in the league.
"Claressa is a once-in-a-lifetime athlete who has already accomplished in boxing what no man or woman has ever done," said Mark Taffet, Shields' manager.
"She now looks to continue to make history by becoming the first man or woman to hold championships in both boxing and MMA simultaneously."
