Marko Arnautovic has joined West Ham from Stoke City in a club-record deal.
The Hammers have paid a fee of £20 million for the Austria international, who scored six goals in the Premier League last season.
Pictures of Arnautovic holding the West Ham shirt were leaked on Saturday prior to the official confirmation, with the 28-year-old signing a five-year, £100,000-per-week contract at the London Stadium.
“It feels special to me to be a West Ham player,” Arnautovic told West Ham's official website.
“Everyone knows that West Ham is a big club, with big history and I’m happy to be a part of it now. I can’t wait to get started.
West Ham have been busy in the transfer market this summer, and have also confirmed that the signing of Javier Hernandez is imminent, after securing the signatures of Joe Hart and Pablo Zabaleta.
“Alongside Pablo Zabaleta and Joe Hart we have brought in three players with vast Premier League experience this summer, and that was one of our key targets as we look ahead to the new season," club chairman David Sulllivan said.
The club began the summer with the intention of signing a goalkeeper, a right-back, a striker and a winger, and Arnautovic appears to be the final piece in Slaven Bilic's jigsaw.