Saudi Prince al-Waleed bin Talal has agreed to sell half his stake in Four Seasons Hotels and Resorts to co-owner Bill Gates, giving him control in a deal that values the luxury hotel operator at $10 billion.

Under terms the companies announced Wednesday, Mr. Gates’s Cascade Investment LLC would pay $2.21 billion for a 23.75% stake in the Four Seasons held by Prince al-Waleed’s Kingdom Holding Company.