Previously a free agent, the 30-year-old has been training with the Premier League's bottom club for the last six weeks and will go straight into the squad for Saturday's FA Cup third round tie at home to West Bromwich Albion.
QPR boss Harry Redknapp said: "Tal's a great professional with vast experience and I'm confident he'll be a really useful addition to the squad.
"His attitude is first class and the fact he can play anywhere across the back four is obviously a big bonus for us.
"He just wants to play. He's not here for the money or anything like that. He just wants to come in and do his best for the club."
Ben Haim, a 63-time Israel international, has been handed the number 21 shirt.
Having joined Bolton from Maccabi Tel Aviv in 2004, Ben Haim made 88 appearances for the Totters and went on to have shorter spells with Chelsea and Manchester City, before playing 55 times for Portsmouth prior to his departure in August of last year.