Steve Watson joined Blues as a coach in August 2012.
The former Aston Villa and West Bromwich Albion defender's is responsible for supporting under-21 development squad manager Richard Beale, plus assisting boss Lee Clark and his management team with first team coaching duties.
Watson previously worked under Clark as his development coach at Huddersfield Town.
Watson's playing career began at Newcastle United, where he came through the ranks at St James' Park alongside Clark.
After more than 200 appearances and seven years with Newcastle he joined Aston Villa in 1998, before going to link-up with Everton and West Brom.
He finished his playing career with Sheffield Wednesday in 2009 having completed more than 550 first team games.