Jenas, who cost £7m when he signed from Newcastle in 2005, enjoyed a good campaign last year, scoring eight goals despite two months out through injury.
The 24-year-old told tottenhamhotspur.com: "Spurs have the calibre of squad that any player would want to be part of.
"The spirit in the squad is terrific, the club is ambitious and undoubtedly moving forward."
"I am very happy here and would love to stay at Tottenham for the rest of my career."
"His goals from midfield are a vital ingredient for us and he is already off the mark this season.
"I am delighted he has committed his future to the Club because JJ has so much talent and is such a positive player.
"He always wants to learn and that is the right mentality to have, he wants to prove that he is a top player and the sky is the limit for him."