Mickelson's participation was announced on Monday, with fellow American Tony Finau also joining the field for the January 30 – February 2 tournament.

Defending champion Dustin Johnson, World No.1 Brooks Koepka and Open champion Shane Lowry are among those previously confirmed to play.

"I am really looking forward to playing in Saudi Arabia in January," five-time major champion Mickelson said in a statement.

"I watched Dustin win the title last year and thought the course looked like an interesting challenge.

"Having so many talented players on show also made it look like a much more established tournament than one in its inaugural year."

The European Tour is strongly supporting the tournament, despite what Amnesty International describes as Saudi Arabia's "heinous human rights record.

The decision means Mickelson will miss the PGA Tour's Phoenix Open, a tournament he has played 27 years in a row, in the city where he went to university.

The Saudi International, to be played on the Royal Greens Golf course adjacent to the Red Sea in King Abdullah Economic City, will offer prize money of US$3.5 million (AU$5.1 million), on top of undisclosed appearance fees paid to attract the top players.

The European Tour is strongly supporting the tournament, despite what Amnesty International describes as Saudi Arabia's "heinous human rights record.