The Cameroon international has fallen out of favour under Spurs boss Andre Villas-Boas and had yet to feature for the north Londoners this season.
|5/2||QPR are 5/2 with BetVictor to win the Championship
But the 29-year-old joins the highly rated midfielder in dropingp down a division, with former Tottenham boss Harry Redknapp having lured them to Loftus Road on a season-long loan.
"Let's go QPR!" said Assou-Ekotto on his Twitter page. "I'll keep one eye on u spurs hv a good luck this season #COYS [sic]".
Assou-Ekotto, who enjoyed cult status at White Hart Lane, made 155 Premier League appearances for Tottenham, scoring four times and proving eight assists.
"I am delighted to come here and really excited," Carroll told QPR's official website. "Harry was a big factor for me because of how he likes the game to be played.
"I've seen what Kyle Walker and Andros Townsend got from their loans at QPR and I hope I can enjoy similar success."