Mickelson, a chief recruiter for the new league, is ending a four-month hiatus by adding his name to the 48-man field.
“I am ready to come back to play the game I love but after 32 years this new path is a fresh start, one that is exciting for me at this stage of my career,” Mickelson said in a statement posted on social media.
Mickelson also said he would be playing the last two majors, starting June 16 in the US Open at The Country Club outside Boston.
He said the “transformative” new league would allow him to focus on a healthier approach to life on and off the course. Mickelson did not mention the signing fee, which is likely to be every bit of the US$125 million ($175m) or more reportedly paid to Johnson.
It will be Mickelson’s first time playing since February 6 at the Saudi International, where he first began to draw attention to how he was leaning when he accused the PGA Tour of “obnoxious greed” in an interview with Golf Digest.
Two weeks later, Alan Shipnuck published excerpts from his unauthorised biography on Mickelson in which the six-time major champion acknowledged Saudi Arabia’s human rights atrocities, including the killing of Washington Post columnist Jamal Khashoggi, but said it was worth getting involved if it meant gaining leverage to make changes on the PGA Tour.
Mickelson also said he and three other top players paid attorneys to write the operating agreement of the new league.
He later apologised for what he said were reckless comments, without mentioning the PGA Tour.
But then he was out of view for four months, skipping the Masters and the PGA Championship, which he had won the year before at age 50 to become the oldest major champion in history.
Mickelson apologised again in Monday’s statement, adding that he “empathises” with those who disagree with his decision to leave the PGA Tour for a league funded primarily by the Public Investment Fund in Saudi Arabia.
“His contributions to the sport and connection to fans around the globe cannot be overstated and we are grateful to have him,” said Greg Norman, the CEO and commissioner of LIV Golf Investments.
“He strengthens an exciting field for London where we’re proud to launch a new era for golf.”
The PGA Tour did not grant releases for any of its 14 members who have signed up for the rival series, a list that also includes Martin Kaymer and Charl Schwartzel.