The midfielder spent the entirety of last season on loan at Barnsley
It's understood that signing a centre midfielder had been Blues boss Garry Monk's priority in the transfer window, with the side looking very short in that area, owing to a long term injury David Davis is still suffering from.
Birmingham confirmed the acquisition of the midfielder on their Twitter, where the news was well received by the Blues faithful - despite Gardner having come through the ranks at arch rivals Aston Villa.
OFFICIAL: Blues have signed Gary Gardner on a season-long loan from @AVFCOfficial.— Birmingham City FC (@BCFC) 9 August 2018
The 26-year-old midfielder becomes @GarryMonk's fifth summer signing.
Full story https://t.co/5Wc4wLA5wK#WelcomeGardner #BCFC pic.twitter.com/eqdTHTDyQ0
Gardner will now join up with his new team mates, including his brother Craig, ahead of the Blues' trip to Middlesbrough. The acquisition of Gardner gives Monk some much needed depth in the central midfield area, and his experience could be crucial for the Blues as they look to improve on last season's disappointing finish of 19th.