Marko Arnautovic has completed his move from West Ham to Shanghai SIPG, the Premier League club have announced.
The 30-year-old Austria international moves to the Chinese Super League champions for a reported £22.4m fee.
He scored 22 goals in 65 appearances during his two-season stay with the Hammers after joining from Stoke in 2017.
"West Ham United can confirm that Marko Arnautovic has joined Chinese Super League champions Shanghai SIPG for an undisclosed fee," read a short statement on West Ham's website.
Arnautovic endured a difficult 2018-19 campaign at the London Stadium, failing in a mid-season attempt to move to China.
He was booed by his own fans in the wake of that situation but signed a contract extension, the length of which was not revealed by the club.
After agreeing the contract extension, he told the club's website: "The fans gave me the power, they gave me the energy and that's why I have to be here and that's why I want to stay.
"I love this club and I will always love this club no matter what. You have decisions you have to make in life, but I say from now it doesn't matter what happens, I will always love West Ham and it will always be a big part in my life."
Arnautovic began his career with Dutch side FC Twente before moving to German club Werder Bremen following an unsuccessful loan spell under Jose Mourinho at Inter Milan.
He moved to England in 2013 and spent four years with the Potters, finding the net 22 times in 125 top-flight outings.
West Ham are set to travel to China later this month to compete in the pre-season Premier League Asia Trophy tournament.
Arnautovic, who has been capped 81 times by his country and played at Euro 2016, will be managed by Portuguese coach Vitor Pereira in Shanghai.
His team-mates will include former Chelsea midfielder Oscar and Brazil international Hulk.
Details of his contract have not yet been announced by the Chinese club.