The 22-year-old has established himself among the club's key players in his two seasons and also become a regular in the England team.
His new five-year deal comes shortly after Christian Eriksen re-committed himself to Mauricio Pochettino's team and amid the expectation Harry Kane and Kyle Walker will do similarly.
Tottenham recruited Dier for £4million from Sporting Lisbon in 2014
Following a season of playing in defence, Pochettino transformed him into the classy defensive midfielder instrumental to much of their progress.
On Wednesday they host Monaco at Wembley Stadium in their first Champions League fixture for five years.
Dier is expected to retain his place and continue his long-term midfield partnership for club and country with Dele Alli after Saturday's 4-0 Premier League win at Stoke.
"There are many reasons I wanted to commit my future to Tottenham," said Dier.
"We have a fantastic squad full of young, exciting players
We've got the new stadium on its way, the fantastic facilities at the training ground, and a fantastic manager who's great for all us young players.
"He really looks after us, and makes sure we keep improving.
"Wembley being filled with 80,000 or more Tottenham fans is going to be an amazing experience
Playing in the Champions League there is very unique, so those two things are going to be fantastic."
Source : PA
Source: PA