The addition of the former Arsenal trainee strengthens manager Lee Clark’s defensive options ahead of the 2013/14 Championship season.
Born in Stockport, Bartley began his career with Bolton Wanderers before joining Arsenal’s Academy in 2007.
He captained the Gunners’ reserve side and made his first-team debut in a UEFA Champions League tie against Olympiakos in 2009.
Successful loan spells at Sheffield United and Glasgow Rangers followed before the youngster made a permanent switch to Swansea in the summer of 2012.
An early-season thigh injury halted his progress last season although he showed promise during five first-team appearances.
The 6ft 4in star has also represented England at youth level.
After completing his move, Bartley told bcfc.com: "It's great news. As soon as my agent mentioned the move then I was all for it because this is a massive club with a massive fan base. I know the manager well and he's a really good young manager who matches the club's ambition."
A full and exclusive BluesTV
interview with the new recruit will follow on bcfc.com.
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