The experienced defender joined Blues in February 2009 on an intial one month contract, which was later extended until the end of the 2008/09 season.
His impressive performances during Blues' promotion-winning Championship campaign saw the full back rewarded with a two year deal in the summer of 2009.
The Dublin-born player began his career as a trainee at Spurs and progressed through the ranks at White Hart Lane to the first team, where he went on to make 270 appearances.
He moved to the Newcastle for a fee of £2 million in August 2004 and made 107 appearances for the St. James' Park outfit over the following four years.
Carr has represented the Republic of Ireland on 44 occasions,