The Championship side will have the services of the defender for the rest of the season.
The 25-year-old has played for Liverpool, before leaving for Bournemouth in 2016.
He was on loan at Seattle Sounders in the United States for the past 18 months.
With the MLS season over, Bournemouth helped him find another situation where he can get first team games.
He will be hoping to use the move to Cardiff as a way to earn a permanent transfer in the summer.