Fox said he was looking forward to joining the GMG board and contributing to the evolution and development of the company.
Last August, Fox ruled himself out of the hunt for a new ITV chief executive to succeed outgoing CEO Michael Grade, pledging to stay with the three-year restructuring plan at the HMV Group, which is due to be finalised this year.
Since his appointment in 2006, Fox has led HMV's turnaround strategy aimed at reducing reliance on traditional revenue streams and transforming the company into a broad-based entertainment brand.
Before joining HMV he was chief operating officer of Kesa Electricals plc with responsibility for Comet in the UK, Kesa's subsidiaries in continental Europe and e-commerce developments.
Prior to his appointment as COO of Kesa, he was managing director of Comet Group, which he led through its de-merger from Kingfisher.
Amelia Fawcett, chair of GMG, said: "We are fortunate to have a world-class contingent of non-executive directors, and it is excellent news that Simon will be joining their ranks."
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