Manuel Lanzini has sealed a permanent move to West Ham, signing a four-year deal.
Co-chairman David Sullivan revealed earlier this week that a deal for the attacking midfielder - understood to be worth in the region of £9.4 million - had been agreed with parent club Al-Jazira to make his loan move permanent.
West Ham have now announced that the 23-year-old has signed a four-year contract with the option of a further two years.
"I am absolutely delighted to have signed and to be able to stay at this club," he told the Premier League side's official website.
"I really feel at home here, and when you feel at home somewhere, you definitely don't want to leave.
"I am very happy and now what I want to do is to keep giving the best of myself.
"We've already done very well, and it's already been a very good season, and when you're so close to achieving your objectives, of course you want to keep dreaming.
"I always had big dreams as a child, but you never know what the future is going to hold. Thanks to God, I'm here, I'm enjoying the city, I'm enjoying the people and I really see my future here."
Lanzini has made 22 appearances in all competitions for West Ham this season, playing a key part in their surprise chase for a Champions League places and run to the FA Cup quarter-finals.