West Ham have finalised the signing of Ecuador striker Enner Valencia after he was given a work permit.
The striker has signed a five-year contract from Mexican club Pachuca for a fee reported to be £12m.
He said: "I want to repay the club in my performances for what they are investing in me."
In a statement, West Ham said they "fought off competition from a host of Europe's leading clubs" for Valencia.
He played over 100 times for Ecuadorian club side Emelec before joining Pachuca in January.
Valencia, who was a right winger until he joined the Mexican side, scored 18 goals in 23 league games last season.
"I really appreciate the welcome I've been given and I'm excited to be here," Valencia, who is no relation to Manchester United's Ecuador winger Antonio Valencia, told West Ham TV.
"I've already watched and read a lot about the club to learn about it - I know the fans are really passionate and I'm really glad to have signed.
"The World Cup was a good tournament for me personally, I scored three times and for my first World Cup it was a good experience, but I hope my next one is better for me and the team.
"Of course, the World Cup gives me confidence to come to Europe and I want to take and advance with this opportunity that West Ham have given to me."
He joins West Ham following the signings of midfielder Diego Poyet from Charlton, striker Mauro Zarate from Velez Sarsfield, Anderlecht's Senegal international midfielder Cheikhou Kouyate and Ipswich full-back Aaron Cresswell.