The 63-year-old Dutchman, who led the Oranje to the 2010 World Cup final in South Africa, has agreed a one-year contract and will begin his new job next week, the Saudi Arabian Football Federation announced on its website.
Van Marwijk has been out of work since being sacked by Bundesliga side Hamburg 18 months ago.
United hope Rangnick link will secure Haaland deal - Paper Round
Palmeiras retain Copa Libertadores with extra time win over Flamengo
Game abandoned as Belenenses name just nine players to face Benfica due to Covid-19 outbreak