"Engineer" will redirect the Frenchman to Manchester City.
West Ham, directed by Manuel Pellegrini, was signed by Samir Nasri. The Frenchman is serving an 18-month sanction for doping and signed for the rest of the season and with the possibility of continuing the relationship for another year.
The 31-year-old midfielder trained with "Hamers" in November, due to the great relationship he had with "Engineer", who had already led Manchester City
"You choose a club and a project for your ambition and I think West Ham has everything to be one of the big teams in London," the Frenchman said.
"I'm returning to the most competitive league in the world, with a team full of ambitions and a coach I know," he said on the club's website.
West Ham will be hosting Brighton and Hove Albion on Wednesday, January 2, for a new Premier League date.