Soucek has signed a four-year contract (credit: West Ham United)
The 25-year-old has agreed to a four-year contract, after initially arriving on loan from Slavia Prague in January.
Soucek has scored three goals since the season restarted in June, in a run that has helped West Ham escape the threat of relegation from the Premier League with a game to spare.
Hammers boss David Moyes said: “I’m delighted that Tomas has signed his permanent contract to secure his long-term future at the club.
“When I came in, we talked about needing another midfield player, to help Declan Rice and Mark Noble, and I think he’s been a really good fit for us.
“He’s a terrific lad with very good physical capabilities. He has scored some really important goals for us, against Chelsea, Newcastle, and Watford.
“We’re glad he’s going to be a West Ham player for a good period to come.”
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Tags: Football, West Ham United