Simpson's departure follows that of Vodafone's chief marketing officer, Peter Bamford, who has been replaced by global consumer marketing director Frank Rovekamp; Simpson had been among those tipped to succeed Bamford. A spokesman said that no decision had been made on Simpson's replacement.
Vodafone has recently decided to devolve centralised responsibility for marketing strategy to individual territories. As a result, it made some 200 redundancies in its marketing department.
Simpson joined Vodafone from Adidas, where he was global head of advertising, in 2002. David Wheldon was brought in to Vodafone as global marketing director above Simpson in 2004.
In May, Vodafone announced the biggest loss -ú14.9bn - in UK corporate history due to a revaluation of its Mannesman takeover.