The 30-year-old has been heavily linked with a move away from the Baggies during the January transfer window after finding first-team opportunities hard to come by at The Hawthorns this season.
Gardner only signed a new two-year contract extension with Albion in October but after being limited to just ten appearances for the club during the first half of the campaign, he now looks set to join former side Birmingham on a temporary basis.
It is believed he will join the Blues on an initial loan until the end of the season, with a view to a permanent deal in the summer, with the Express & Star reporting the versatile midfielder will undergo a medical over the coming days.
Gardner enjoyed a productive spell at Birmingham between 2010 and 2011, helping the Blues to League Cup glory during his time at St Andrew's.
West Brom last week