Asked specifically about Saudi Arabia's human rights record and the murder of journalist Jamal Khashoggi, Mickelson added: "I certainly do not condone human rights violations.
"And addressing what happened to Jamal Khashoggi is awful. But I have seen the good that the game of golf has done throughout history. And I really believe that LIV can be good for the game of golf as well.''
Mickelson joins players such as two-time major winner Dustin Johnson - who has reportedly signed a deal worth $150m to play in the series - England's former world number one Lee Westwood, Ryder Cup stalwart Ian Poulter and Spaniard Sergio Garcia.
In an interview with the Washington Post, Norman said 15-time major winner Tiger Woods had been offered a "mind-blowingly enormous" deal to take part in the series.
"We're talking about high nine digits," he added.
Norman has shelved plans to run the series as a league format, instead each event will run as an invitational tournament until 2024.
"Phil Mickelson is unequivocally one of the greatest golfers of this generation," said Norman. "His contributions to the sport and connection to fans around the globe cannot be overstated and we are grateful to have him.
"He strengthens an exciting field for London, where we're proud to launch a new era for golf."
This initial $255m (£202m) invitational series will feature six more regular season tournaments in 2022 - four in the United States, one in Thailand and one in Saudi Arabia - each having the same $25m (£20m) prize fund, meaning every leg of the series is more lucrative than the richest tournament on the PGA Tour.
The events will feature a team and individual competition, with 12 captains selecting three players in a draft-style format. Each day, the teams of four will tee off at the same time on different holes in what is termed a 'shotgun start'.
Each event's individual winner will take home $4m - by way of comparison, the PGA Tour's flagship event, the Players Championship, earned Cameron Smith $3.6m for his victory in March, while Collin Morikawa won $2m for his Open Championship victory in 2021.
The eighth and final event, at Trump National Doral in Miami in October, will be a $50m 'Team Championship' matchplay knockout tournament featuring 12 teams. The winning team will receive $16m, with each of the four players earning a 25% cut.
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