West Ham finalised a deal for St Etienne's Brazilian striker Ilan on deadline day.
The Hammers had been strongly linked with a move for the South American and he was at Upton Park on Monday for talks.
The 29-year-old, who has won three caps for his country, struck an accord with West Ham and is now set to spend the remainder of the 2009/10 campaign with the Premier League outfit.
There is an option available to both parties for a permanent two-year deal to be put in place at the end of the season.
He will move to East London as a free agent, after six years spent in France with St Etienne and Sochaux.
Ilan still had six months left to run on his contract at Stade Geoffrey-Guichard, but has been released from that agreement.
He becomes Gianfranco Zola's third attacking signing on a busy day of transfer activity, with Benni McCarthy and Mido having also agreed to join the Hammers.
"I am extremely happy to be here and I hope to play as soon as possible. I look forward to the challenge," Ilan told Sky Sports News.
"It was an easy decision to come here. It is one of the biggest leagues in the world.
"My aim is to the best I can and score goals. I want to start with a bang.
"I am delighted to be here and I am looking forward to enjoying a long-term relationship with West Ham."