Tottenham had reportedly already agreed a fee for the 18-year-old before QPR entered the race.
Now, however, the R's have confirmed Manning's signing - and the QPR boss feels the teenager is a 'good gamble'.
“Ryan is a young lad who has been chased by a number of top clubs in the Premier League. We have managed to secure him and bring him here, so we’re delighted with that," Redknapp told QPR's official website.
“He is a busy player who can play off the left or in behind the striker. He is still young and has a lot to learn but it’s a good gamble for us to take.
“I think he feels he has got a real chance of playing for us here, and hopefully he will progress with us. We’re certainly pleased to have him.”
Interestingly, Manning admitted that former Tottenham striker and coach Les Ferdinand was instrumental in persuading the 18-year-old to move to Loftus Road.