Dembélé joined Tottenham from Fulham in August 2012 for £15 playing 143 times in all competitions and scoring nine goals
Also read: Mousa Dembele hails Tottenham
With just 18 months left on his contract, Spurs chairman Daniel Levy made the midfielder’s contract extension a priority.
“I am very happy I've signed and I'm happy to be part of our future,” Dembele said.
“The way we're playing, the way the club is developing, everything is very good and everyone wants to be part of this team and this club.
“That's why I'm proud to extend my contract.”
Dembele has become an important player for Spurs under Mauricio Pochettino with four goals in 20 appearances so far this season.