Jordon Mutch has become Malky Mackay's second summer signing. The England U21 international folows keeper Joe Lewis to CCS.
Mutch started at Birmingham City since 2007 as a trainee. He had loan spells at Hereford, Doncaster and under Malky Mackay at Watford.
Last season he secured a place in the Birmingham first team becoming a regular starter after Christmas. He played in Birmingham's two legged play off defeat against Blackpool.
"I'm delighted that we've managed to bring Jordon in here at Cardiff City," Mackay told Cardiff's official website.
"He's a talented player who I know well, both from my time working with him back in Watford and from the progress he's made at Birmingham City.
"Jordon is a top player with great potential for a big career in the game, which we hope to see him fulfil with us here at Cardiff City.
"His record of playing right through from under 17s to under 21s for England is also impressive and Jordon will no doubt make a great addition to the squad that we are building here in South Wales."