The deal replaces the five-year contract he signed in February 2015 and will reportedly earn the 23-year-old captain £80,000 ($101,000) a week.
"It's amazing. Everyone knows how much I love this team and what I feel for this club," Kane, who finished top scorer in the Premier League last season with 25 goals and has hit the net five times already this term, told Tottenham's website on Thursday.
"To sign another contract is a special feeling. We've got a great, young squad and the club is moving in the right direction."
After coming through Tottenham's academy, Kane made his debut in 2011 but it was towards the end of the 2013-14 campaign that he first made an impact.
The following season he scored 21 goals in the league and he now has 70 for Spurs in 137 appearances.
Kane has only recently returned from a seven-week absence with an ankle injury but has scored four goals in his last four matches.
Kyle Walker, Christian Eriksen, Eric Dier, Danny Rose and Dele Alli have all extended their deals at Spurs.