Kane has signed a contract which ties him to Spurs until the summer of 2017, but the 19-year-old will spend the rest of this term in the Championship.
The Londoner's latest loan comes after a mixed spell at Norwich during which he made just five appearances and suffered a broken bone in his foot.
But last season brought seven goals at Championship level with Millwall, and Leicester boss Nigel Pearson hopes Kane can revive a promotion campaign which has faltered with back-to-back defeats.
Pearson said: "He'll hopefully bring more goals, a fresh impetus, and it keeps that competition really keen.
"He's a player that we know quite a lot about and I'm delighted that we've been able to secure him for our squad and it will hopefully be a positive move all round.
"It's always important that if you bring players in on loan, they've got to have a hunger for success, and I'm confident that we've got another player coming into our ranks that with bring a lot of positive qualities."