West Ham have signed France international midfielder Dimitri Payet from Marseille on a five-year contract in a deal worth more than £10m.
The Hammers say Payet, 28, has signed for "an eight-figure" fee, although exact details have not been released.
"We have signed a world-class player. If he was 22 he would be £30m plus, but he's still in his prime," said co-chairman David Sullivan.
There is an option for another 12 months beyond the initial contract.
Payet has set up 51 goals over the past six Ligue 1 seasons with St-Etienne, Lille and Marseille, according to his new club.
"I like attacking football and the fact they're counting on me to help achieve that gives me a sense of responsibility," he said.
He follows the signings of Spanish midfielder Pedro Obiang and Republic of Ireland goalkeeper Darren Randolph.
Payet has played 15 times in the Champions League, and will be available for West Ham's Europa League campaign, which begins on 2 July under new manager Slaven Bilic.
|Factfile: Dimitri Payet|
|France caps: 15. Goals: 1 (in friendly v Belgium last month)|
|Career club matches: 332. Goals: 60|