West Ham signed Italy defender Emerson Palmieri from Chelsea in a deal worth a reported £15 million ($17 million) on Tuesday.
Emerson has agreed a four-year contract with the Hammers, with the option of a further one-year extension.
The 28-year-old left-back was born in Brazil, but moved to Italy in 2014 and was eventually granted citizenship.
He struggled to break into the Chelsea team in five years at Stamford Bridge and spent last season on loan at Lyon.
Emerson has won 27 caps for Italy and played in their win over England in the Euro 2020 final at Wembley.
“I’m very happy to be here and to arrive here. It’s a big challenge for me, it’s a big team, so I’m very happy to be here and I’m ready,” Emerson told West Ham’s website.
“Personally, since the first day I arrived here in England, I always saw the big clubs and I always watched the big games and I knew the history about West Ham.
“The history is so big for this team and so when I knew about the interest for sure I said ‘Yes, let’s go, I want to go there’ and I’m here now! I can’t wait to get started in a West Ham shirt.”
Emerson becomes West Ham manager David Moyes’ seventh signing since the end of last season.
“He is an experienced player with a good pedigree, who has enjoyed great success at both club and international level in recent years,” Moyes said.
“He will give us strong competition in defensive areas and brings a winning mentality that we are looking to build here at West Ham.”
West Ham lost 2-0 at home against Brighton on Sunday and sit bottom of the Premier League after three straight defeats, the club’s worst start to a season in 51 years.