The 27-year-old joined West Ham on a season-long loan last summer and has impressed at Upton Park.
He told the club’s official website: “It is a great joy for me to have signed permanently for a club that believed in me and gave me the opportunity to play in the Premier League.
“My goal is to keep developing as a player here, working for the manager and his staff. I am very happy to be here and there is a great atmosphere with my team-mates.
“The fans here are incredible because they are always behind the team. Sometimes they help us to get the victories but even when we lose they are always there for us.
“They have played an important part this season and we hope to give them a special present at the end of this season by qualifying for Europe.”
