The 30-year-old links up with Neil Warnock's side and comes with a wealth of Championship experience, having spent the last six years with the likes of Rovers, Millwall, Ipswich Town and Bolton Wanderers.
"Liam is a player that I've always liked and I think he'll enjoy playing for me," Warnock told the Cardiff website.
"I think we needed a player of his quality to come in, especially with the injury we have to Kads (Kadeem Harris) at the moment. I'd like to thank the board for allowing us to bring him on loan until the end of the year."
The Bluebirds have made the perfect start to the new Championship season, sitting top of the early table after winning all five of their opening games.