The club confirmed he was in a stable condition on Saturday and have now followed up with another update on the Hammers striker in a statement on Sunday.
It read: "West Ham United can confirm Michail Antonio has undergone surgery on a lower limb fracture following a road traffic accident on Saturday afternoon.
"Michail will continue to be monitored in hospital over the coming days.
"Everyone at the Club wishes Michail a speedy recovery and wishes to express its sincere gratitude to the football family at large for the overwhelming support shown since yesterday's news, as well as extending a heartfelt thank you to the emergency services and first responders who attended to Michail in the immediate aftermath of the incident, and the medical team who continue to aid him in his recovery.
"The Club will provide further updates when appropriate."
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Pictures emerged on social media of Antonio's smashed up Ferrari in Essex - close to West Ham owner David Sullivan's house - on Saturday.
The Hammers forward was trapped inside his vehicle for almost an hour as emergency services worked tirelessly to free him.
He was airlifted to a hospital in central London.
The 34-year-old's ex-wife Debbie has travelled from her home in Manchester to be at Antonio's bedside.
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A statement from Essex Police on Saturday said: "We were called shortly after 12.50pm on Saturday 7 December to Coppice Row, Epping, following reports of what is believed to be a single vehicle collision involving a Ferrari.
"Emergency services attended and the driver has been taken to hospital.
"The vehicle has been recovered and we are no longer on scene. An investigation will be carried out by our Roads Policing Unit."
Essex County Fire and Rescue Service said it attended the scene of the accident in Epping on Saturday afternoon and released a man trapped in his car.
"Crews were called at 1.02pm this afternoon after reports of a road traffic collision involving one car," it said.
West Ham issued their thoughts and prayers after the news broke, and plenty of other clubs followed suit.
Premier League players also sent their support to Antonio.
The Jamaica international has made 323 appearances for West Ham since signing from Nottingham Forest in 2015.
He's also played for Reading and Sheffield Wednesday amongst other clubs during his career.
Antonio has made 15 appearances so far this season in all competitions, scoring once and bagging one assist.