Bogle helped Cardiff achieve promotion to the Premier League last season but now joins Birmingham in what will be his second spell with the Championship club after spending two years there during his youth career.
A statement on Birmingham's website reads: "Blues have today completed the signing of Cardiff City striker Omar Bogle on a season-long loan.
"It is a second spell at Blues for the 25-year-old forward, who was with the club's Academy between 2009-2011 before being released.
"Bogle has been allocated the number 14 shirt by Blues."
The forward scored three goals in ten Championship appearances for Cardiff last season but struggled for regular appearances, being sent out on loan to Peterborough in February.
His path to the first team looked even trickier earlier this summer when Cardiff completed the signing of Bobby Reid from Bristol City, who was prolific during the Robins' ultimately unsuccessful bid to reach the play-offs.
Bogle will try to help Birmingham improve upon their finish of 19th in the Championship next season as Garry Monk looks to push on after their 2-2 draw with Norwich on the opening day of the 2018/19 term.