Lee Bowyer joined Blues on a free transfer in August 2009, after an impressive loan spell at St. Andrew's the previous season.
The midfielder signed a two-year contract with the club.
Bowyer made 17 appearances for Alex McLeish's side in the 08/09 season, scoring one goal on his debut against Cardiff City in January.
He was an integral part of the Blues side that gained promotion to the Premier League following his loan switch from West Ham United.
The former England international began his career at Charlton before switching to Leeds United in 1996 for a fee of £2.8 million - a then record transfer for a British teenager.
He then returned to his boyhood club West Ham in 2003, before returning north again this time to Newcastle United six months later.
Upton Park beckoned again three years later before his loan switch to Blues in January 2009.