Dembele quickly became a favourite of the Cottagers faithful last season.
He told FulTime: "They got behind us last season and even in that disappointing defeat against Liverpool they kept on until the end. The atmosphere is fantastic and when you walk out from the Cottage they are right there.
"I'm hopeful that we can have many things to celebrate over the coming years. They have welcomed me to their club and for that I am very thankful. When I see fans with Dembélé on the back of their shirt it makes me very happy. It's nice to be appreciated and I would like to make them happy in return."