QPR have forked out a club record fee to secure the signing of Anzhi defender Christopher Samba on a four-and-a-half year deal.
That deal is now complete, with Samba joining for an undisclosed club record fee, subject to the player receiving international clearance.
The Congolese defender, who was with Blackburn until last February, will wear the number five shirt at Loftus Road and fills the void left by Ryan Nelsen after his decision to become Toronto FC head coach.
"This is an unbelievable signing," Redknapp told the club's official website, www.qpr.co.uk. "(Chairman) Tony Fernandes deserves a lot of credit for this one - he has worked so hard on bringing him in.
"I was speaking with him a month ago and he asked me who I would want to sign if Ryan Nelsen left, he asked me to give him a couple of names.
"I said to him 'Well, these aren't possible to get but if you're asking me who I'd have, I'll give you a couple of players'. One of them was Chris Samba. The next thing I know he's telling me that he's working on bringing him in! It's amazing.
"Chris is just what we need. He's a monster. Great in the air, quick, a leader, strong, fantastic in both boxes, hard as nails. He's a proper centre-half."
Samba joins a side bottom of the Barclays Premier League and four points adrift of safety - but believes QPR can get out of their current predicament, and he said: "I'm delighted to be back in the Premier League. It's the best league in the world to play football.
"I've been linked with the club for a long time. With Harry here, though, he is really passionate and he wants to do something with the club. Unfortunately things haven't gone the way the club would have wanted so far this season but there's still a lot of time and I'm sure we can get out of it."