The Hammers revealed earlier today that a £25million transfer fee had been agreed.
And following a medical this evening, 29-year-old Payet has now completed his move back to France.
The playmaker has penned a four-and-a-half year deal with Marseille.
Dimitri Payet has ended his one-and-a-half year stay at West Ham
Payet's departure brings to an end a turbulent season at West Ham.
Slaven Bilic revealed earlier this month that the France international had refused to play for the club.
Despite interest from top Premier League sides as well as an offer from China, Payet was set on a return to former club Marseille for personal reasons.
Twitter reacts as Marseille agree fee with West Ham for Dimitri Payet
Sun, January 29, 2017
Express Sport brings you all the best tweets as Marseille agree a fee to sign West Ham playmaker Dimitri Payet
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Marseille agree a fee to sign West Ham playmaker Dimitri Payet
West Ham fans were left angry at the manner in which Payet brought his Hammers career to a close.
Bilic and members of the squad have outlined no player is bigger than the club, and they were ready to cut ties with the wantaway star.