London - Cardiff signed Republic of Ireland defender Greg Cunningham from Preston on Wednesday in a deal worth a reported £4 million.
Cunningham, 27, agreed a three-year contract with the newly-promoted Premier League club after impressing Bluebirds boss Neil Warnock in the Championship this season.
"It's fair to say that I've been an admirer of Greg for a number of years and that he's consistently been one of the best left-sided defenders for club and country," Warnock told Cardiff's website.
"We're delighted to have his experience and knowledge so as to supplement Joe Bennett who had a great time last season.
"I anticipate that Greg coming in will give us a lot of strength down that left-hand side."
Cunningham's arrival comes after Cardiff signed Norwich winger Josh Murphy on Tuesday in a deal thought to be worth around £11 million.
Warnock has targeted five signings as Cardiff seek to strengthen their squad following promotion to the top-flight.
Cunningham, who started his career at Manchester City, made 111 appearances for Preston after joining from Bristol City in 2015.