The 28-year-old centre-back signed a four-and-a-half-year contract on Thursday and will be free to join QPR's survival campaign once receiving international clearance.
Tottenham Hotspur's surplus midfielder Jermaine Jenas also joined the West London club on an 18-month deal along with Spurs team-mate Andros Townsend who agreed a loan deal.
Peter Odemwingie's desperate attempt to force through a move from West Bromwich Albion ended in embarrassing failure.
The West Brom striker drove to QPR's Loftus Road ground without the permission of his club but only got as far as the car park with Rangers not prepared to talk.
West Brom later issued a statement condemning Odemwingie's attempts to leave. "No agreement has been reached with QPR over striker," West Brom said on their website.
"The club can confirm they have held further discussions with QPR today but those talks have so far proven fruitless and no agreement has been reached.
"Albion would also like to make clear that Peter has not been given permission to speak to QPR about a potential move."
Samba, a Congo international with 26 caps, spent five years in England with Blackburn Rovers from 2007-12 and joined Rangers after an 11-month stint at Russian club Anzhi.
"This is an unbelievable signing," QPR manager Harry Redknapp said on the club website.
"[Chairman] Tony Fernandes deserves a lot of credit for this one - he has worked so hard on bringing him in.
"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, who made 23 appearances for the Russian club after signing last February, is a direct replacement for the departing Ryan Nelsen who was named head coach of Major League Soccer club Toronto this month.
"I know what is going on with the project here. There is a very important fan base here - I've played at Loftus Road before and it's fantastic," said Samba whose transfer fee was reported to be 12.5 million pounds by British newspapers.
"I wouldn't be here if I didn't believe we could get out of trouble."
Jenas, a former England international, has been out of the picture at Tottenham and the 29-year-old has spent time on loan at Aston Villa and Nottingham Forest in the last two seasons.
He is reunited with Redknapp after working under at Tottenham.
"The fact that Harry Redknapp was here was a big factor. There's a big challenge ahead of us in staying in league and I want to be part of it," Jenas told Sky Sports.
"There's no time to waste in this situation, so we need to hit the ground running, starting on Saturday with a win."
QPR, who play Norwich City on Saturday, are bottom of the Premier League with 16 points from 24 games.
