Andre Ayew has joined West Ham from Swansea City on a three-year deal, the club confirmed on Monday.
West Ham said Ayew, 26, had joined for a club-record fee, confirmed by chairman David Gold to be £20.5 million.
After scoring 12 goals last season in his first Premier League campaign following a move from Marseille, Ayew signed on at West Ham until 2019, with an option for two additional years.
"I am very proud and happy to be at this magnificent Club. I am happy to be playing for these fans and I hope to make the people very happy here," Ayew told West Ham's website.
"The club have a lot of ambition and have a great manager. They want to become a bigger club every year and with the new Stadium and a new training ground, you can feel they are moving onto another level and I want to be part of this project.
"I want to train hard, do my job and show that I deserve to play for West Ham United. I want to give back to the manager and the fans the confidence they are showing me."
Ayew has also starred for Ghana in 67 international appearances, scoring twice at the 2014 World Cup and three times at the 2015 African Nations Cup.
The move comes on the same day that the Hammers announced the signing of Olympiakos left-back Arthur Masuaku in the region of £6 million.