Rooney, 23, was a free agent after his contract with Inverness expired at the end of last season.
He scored 21 goals in 42 games for the Clydesdale Bank Premier League club during the 2010-2011 campaign.
He becomes Blues' fourth signing of the close season follwing Marlon King, Chris Burke and Morgaro Gomis into St Andrews.
Source: PA
Source: PA