Carr's current deal was due to expire next summer but the 33-year-old right-back has extended his stay via a 12-month option being added to the contract.
Carr was persuaded out of retirement by Blues boss Alex McLeish 18 months ago. He has been one of Blues' most consistent performers and played a major role in them finishing ninth in the Barclays Premier League last season.
Source: PA
Source: PA