Jonathan Calleri is relishing the chance to prove himself in the Premier League after completing a loan move from Deportivo Maldonado.
West Ham recently announced the Argentine attacker was set to make the move to east London and he has now joined his team-mates in training at Rush Green.
The 22-year-old received international clearance for his switch from the Uruguayan club on Tuesday and is in Slaven Bilic's squad for this week's Europa League play-off clash with Astra Giurgiu.
"I am very happy to have signed for West Ham," Calleri told the club's official website.
"This represents a fantastic new challenge for me and I am really looking forward to it. The Premier League is the best league in the world and so I am delighted to have this opportunity to play in such a prestigious league.
"It is a new chapter for me and so I am excited to get started here and to fit in as quickly as possible, so that I can be as useful as possible to my new teammates and manager.
"These are exciting times for me personally and I am motivated to adapt my game to this new environment. I am a player who always tries to work as hard as I can and to do my best for the team."
Calleri becomes the sixth Argentine to play for West Ham after Lionel Scaloni, Javier Mascherano, Carlos Tevez, Mauro Zarate and Manuel Lanzini.