However, Gardner had already outlined his intention to retire from playing and concentrate on coaching.
That came in November when it was announced that Gardner would become First Team Coach to help assist Pep Clotet.
So when his playing contract expires on 30 June, he will move full-time into the coaching position.
The upshot is that Gardner's 15-year career as a player is to finish.
A starter in Blues 2011 Carling Cup Final winning team, the midfielder is in his second spell at the Club.
He has made 125 appearances, scoring 16 times.
The 33-year-old's last appearance was as captain to a young side in the Carabao Cup at Portsmouth in August.
Gardner joined Blues from Aston Villa, where he came through the youth ranks, in January 2010.
He famously scored the winning goal in the Carling Cup Semi-Final against West Ham United in extra-time to take Blues to Wembley.
And in 2010/11 season he was top-scorer with 10 goals, his trademark powerful shooting off either foot from range and ability to arrive late into good positions serving him and the team well.
After Blues were relegated, Gardner was the first of several players who were told they had to be sold. He joined Sunderland and then it was on to West Bromwich Albion in May 2014.
It was back to Blues initially on loan in January 2017 under Gianfranco Zola - the first time in his career he had played in any division other than the top-flight.
The deal became permanent and the more experienced Gardner became an influential figure in the dressing room and latterly so on the training pitches at Wast Hills.
The Club would like to thank Craig for everything he did as a player and we look forward to the new chapter with us as First Team Coach.