The 23-year-old Co Down golfer signed with the luxury hotel company when he was 18, and during his five years with them he has won two majors and become the world number one.
"Jumeirah became my first corporate sponsor when I turned professional back in 2007, and I would like to thank everyone at the company for their support in helping me become the player I am today," he said.
But McIlroy is now expected to join sportswear company Nike for ten years in a £156 million deal.
In a statement, Jumeirah Group's Gerald Lawless said, "We are extremely proud of Rory's rise to the number one spot."
Mr Lawless added that Rory has "a great future ahead of him" and wished him continued success.
Nike is the current sponsor of Tiger Woods, world number three, who signed one of the most lucrative deals in golfing history when he joined company as he turned pro in 1996.