West Ham announced the sale of Marko Arnautovic to Chinese champions Shanghai SIPG in a terse, two-line statement.
The value of the deal was not disclosed in a statement on Monday from West Ham, who offered no thanks for the Austria forward's 22 goals in two seasons.
The club's Twitter account message was even shorter: "Marko Arnautovic departs ."
British media reported the transfer fee was around STG22 million ($A39 million).
Relations between West Ham and Arnautovic have been tense since he sought a move to China in January, and got worse this offseason.
Arnautovic leaves despite signing a contract extension in late January.
The 30-year-old forward was a club record STG20 million signing from Stoke in 2017.
At Shanghai, Arnautovic will join up in attack with former Brazil internationals Hulk and Oscar.
Australian Associated Press