West Ham have completed the signing of Olympiakos left-back Arthur Masuaku.
Masuaku, 22, has signed a four-year deal, the Hammers confirmed in a statement.
West Ham boss Slaven Bilic confirmed after Sunday's friendly defeat to Juventus that the club were closing in on a double deal for Masuaku and Swansea City forward Andre Ayew.
Masuaku was in attendance for the game at London Stadium after West Ham agreed a fee in the region of £6 million.
He told West Ham's official website: "It's a big honour for me to be part of this club. I was speaking with my agent about some opportunities, but when he told me about West Ham and also the coach, I didn't think twice, so in my mind, it was West Ham.
"To be able to play with players like Dimitri Payet, I was thinking on the way here, it's going to be crazy! I can't wait to play with him and also all the rest of the team.
"For me, the Premier League is the biggest league in the world. When I was 18, my target was to come here, so now I am here, I have to prove myself to the fans and to the team so that I can play for this big club."
- West Ham United FC (@whufc_official) August 8, 2016
West Ham have moved to strengthen their options at left-back after Aaron Cresswell was injured during preseason.
Inter Milan's Davide Santon was expected to join last week but the former Newcastle man failed a medical.
The Frenchman arrives in the Premier League having won two Greek Superleague titles and the Greek Cup in two seasons with Olympiakos.
Masuaku has played for France at under-18 and under-19 level and played against Arsenal and Bayern Munich in the Champions League last season.
He is likely to be available for next Monday's Premier League opener with Chelsea.