Fulham's approach was enough to see off interest from Premier League rivals Birmingham City.
The forward, who has won 28 caps, resolved to work hard to make a success of his move to England.
"It has always been a dream to play in the Premier League and I will make sure that I make the most of this opportunity," Dembele added.
"I understand that Fulham has a strong squad, so I am prepared to work hard for the Manager and take my chance to impress him, and my team-mates."
Hughes's attempts to secure Wales striker Craig Bellamy on loan from former club Manchester City were foiled when the player opted for Championship side Cardiff instead.
Zoltan Gera was often pushed forward as a foil for Zamora last season after Hughes's predecessor Roy Hodgson allowed strikers Diomansy Kamara and Eddie Johnson to leave Craven Cottage on loan for the second half of the campaign.
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