Angelo Ogbonna has left Juventus to sign a four-year deal with West Ham.
The deal was confirmed on Friday evening, after the Premier League club beat off competition to land the defender.
Although the Hammers started negotiations with Juventus early this week, Everton and Southampton tried to hijack the transfer.
West Ham will pay the Champions League finalists £7.9million over three years.
Ogbonna, who has won 10 times by Italy, has found first-team football hard to come by at the Serie A club.
He has been capped 10 times by Italy, but struggled to secure regular first-team football at Juventus.
He becomes Slaven Bilic’s third key signing of the summer, following the signings of Pedro Obiang and Dimitri Payet.