The new deal will keep the 63-year-old at White Hart Lane until the summer of 2013.
Redknapp managed to guide Spurs to a fourth finish in the Premier League last season.
“I am now committed to Spurs for the next three years and of course I am pleased by that,” Redknapp told ESPN.
“That has made me think about how long I want to stay in the game and – who knows – I might stay with Spurs many more years than 2013.”
A short statement on Tottenham’s official website read: “The club is delighted to announce that we have extended the contract of manager, Harry Redknapp, until 2013.”