Arnautovic quit the London Stadium for Shanghai SIPG on Sunday night in a deal thought to be worth around £23m.
The Austria international’s switch comes after he first agitated for a lucrative move to China back in January.
West Ham chiefs, clearly unhappy about Arnautovic turning his back on them six months after signing a contract, have now confirmed his departure.
And it’s safe to say they left no room for sentiment towards the 30-year-old, who joined them from Stoke in 2017.
A brief West Ham statement read: “West Ham United can confirm that Marko Arnautovic has joined Chinese Super League champions Shanghai SIPG for an undisclosed fee.
“The 30-year-old Austrian departs after two seasons at London Stadium, during which he scored 22 goals in 65 appearances in Claret and Blue.”
Arnautovic leaves West Ham having been their top scorer last season with 11 Premier League goals.
The onus will be on Felipe Anderson and co. to step up in his stead over the course of the 2019/20 campaign.
West Ham have a number of options in their sights as they look to replace Arnautovic.
Foremost among them is Maxi Gomez, who has enjoyed a stellar couple of years at Celta Vigo.
Gomez slammed in 13 goals in 33 La Liga appearances for Celta last season.
And his form has attracted attention from Valencia, who can offer him Champions League football.
Salomon Rondon, who spent last year on loan at Newcastle, has also been linked with West Ham.
And, with West Brom stuck in the Championship for another 12 months, he might fancy a move to London.
West Ham have been credited with interest in Bournemouth hotshot Callum Wilson as well.
They could, though, face a battle with Tottenham if they launch a raid for the England international.