Despite manager Neil Warnock claiming that it would be a quiet day of activity for the Welsh outfit, the Bluebirds brought in two new faces late on and also offloaded a number of fringe players, including Matthew Kennedy, Stuart O'Keefe, Matty Kennedy and Craig Noone.
Bryson completes what Warnock hopes will be a title-winning squad, bringing with him six years of experience at Championship level with Derby.
Speaking to Cardiff's official website, experienced boss Warnock said: "Of all the players I wanted to sign, Craig Bryson has been at the top of my list for a very long time.
"I never thought we'd be able to do the deal to get him over the line, so I must thank Vincent [Tan], Mehmet [Dalman] and Ken [Choo] for making it possible for us."
Cardiff top the Championship standings after five games following a perfect start to the season.