Fox, who was with the company as head of music since 2005, left the company earlier in May, an unidentified source told THR. The departure came after an announcement from new president Marc Graboff, who took the helm in January.
Fox played a key role in "American Idol" summer tour sponsorships and was active in the careers of some of the reality show's finalists, including Haley Reinhart, the entertainment industry publication said.
Cyrus' former manager, Jason Morey -- the two split in February -- has been brought in to CKx to handle some of Fox's former duties, THR reported.
Celebrity Breakups and divorces of 2014 [PHOTOS]