James Beattie was appointed as Blues' First Team coach in March 2018 as part of Garry Monk's backroom staff.
He had previously worked with Monk in similar roles at Swansea City, Leeds United and Middlesbrough.
A former striker, and ex-England international, Beattie turned out for nine sides over a 17-year playing career.
His longest spell was spent at Southampton, where he stayed for seven seasons and made over 230 appearances, scoring 76 times.
He later turned out for Everton, Sheffield United, Stoke, Rangers and Blackpool, before finishing playing whilst with Accrington Stanley in 2014.
After hanging up his boots, Beattie managed Stanley for 16 months, before joining Monk's coaching staff at Swansea in 2015.