The former Republic of Ireland international made almost 500 appearances for Tottenham Hotspur, Newcastle and Birmingham.
The 36-year-old, who won 44 caps for his country, made his professional debut for Spurs in 1993 alongside the likes of Gary Mabbutt and Teddy Sheringham.
Carr first announced his retirement in December 2008 after failing to find a club following his release from Newcastle, but he was persuaded to reverse that decision two months later by Birmingham.
He went on to make over 100 appearances appearances for Blues, and as captain led the club to a ninth-placed finish in the Barclays Premier League in 2010 and Carling Cup glory a year later.
However, Carr has now gone into retirement for a second time after admitting defeat in his battle against a long-standing knee problem.
"I am going on 37 and now is the time to bow out," Carr told the Birmingham website. "I felt okay in pre-season but my knee just crumbled away.
"Three operations in 18 months basically told me it had had enough. It just wasn't meant to be in the end.
"The fans have been brilliant with me since I came in and I have had a great relationship with them.
"I will never forget that day lifting the cup. It was a big, big thing for me."