West Ham signed England midfielder James Ward-Prowse from Southampton on Monday in a deal worth a reported £30 million ($38 million).
Ward-Prowse agreed a four-year contract with the Hammers as he makes a quick return to the Premier League following Southampton's relegation.
The 28-year-old made 410 appearances for Southampton and was captain as they crashed out of the Premier League last season.
He arrives at the London Stadium to fill the void left by fellow England midfielder Declan Rice's £105 million move to Arsenal in July.
"From the outside looking in, this is a club that has been on the rise for a number of years now and coming off the success in the UEFA Europa Conference League last year," Ward-Prowse said.
"You can feel there is real momentum around this club. It's great to be a part of it and I can't wait to play my role in the games to come."
Ward-Prowse spent two decades on the south-coast after joining Southampton's academy at the age of eight.
During his time at St Mary's, he earned 11 England caps and scored two goals for his country.
Ward-Prowse scored 17 Premier League free-kicks for Southampton and needs just one more to draw level with the competition record held by David Beckham.
He becomes West Ham's second major signing since the end of last season, following their recent swoop for Ajax midfielder Edson Alvarez.
"When I think about my game, it is based on hard work, graft, and giving 100 per cent. West Ham has always been a club that epitomises that," Ward-Prowse said.
"I feel as though I will fit straight in and I can promise I will give my all for this football club in my time here."
The Hammers opened their season with a 1-1 draw at Bournemouth on Saturday and Ward-Prowse could make his debut in Sunday's London derby against Chelsea.
