The 26-year-old was a free agent having left Leyton Orient last month after triggering a release clause in his contract following the O’s relegation from League One last season, having made 42 appearances.
Lowry, who can play at either centre-back or left-back had a successful trial at Blues during pre-season. He featured in the friendly fixtures against Kidderminster Harriers and Benfica B, and scored the equaliser in the Harriers game.
The Perth-born player moved to England in 2005 as a 16-year-old to join Aston Villa, where his performances as a teenager saw him earn a professional contract.
During his time at Villa, he spent four spells out on loan with Plymouth Argyle, Leeds United , Sheffield United and Millwall.
After three years at Villa Park he left in 2012, having made just three substitute appearances for the club to join Millwall on a permanent deal.
He was a key member of the Lions side that reached the semi-final of the FA Cup, before leaving the South London side in the summer of 2014, having made 91 appearances to join Leyton Orient.