McDowell was also formerly with Chandler at ISM, but made his move before winning last year’s US Open.

It follows his decision to end his association with International Sports Management (ISM).

McIlroy said: "I would like to sincerely thank Andrew ‘Chubby’ Chandler and his team for their guidance, representation, and management over the past four years, since turning pro.

"Chubby and his team have played a very important role in my success to date. I have made great progress under their management and for that I will always be grateful.

"I am now keen to move onto the next stage of my career and I feel this will be facilitated by a fresh view and a new structure around me. Therefore I am delighted to be joining Horizon and I look forward to working with my new team."