Cardiff have made Preston defender Greg Cunningham their second summer signing.
The 27-year-old Republic of Ireland international joins the Premier League newcomers on a three-year deal.
The fee has not been disclosed but is thought to be in the region of £4million.
"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," manager Neil Warnock told the official Cardiff 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 £11m.
Warnock has targeted five summer signings as Cardiff seek to strengthen their squad following promotion to the top flight.
Cunningham made 111 appearances for Preston after joining the Sky Bet Championship club from Bristol City in 2015.
He started his career at Manchester City and had loan spells at Leicester and Nottingham Forest.