The 22-year-old returns to the Welsh club with Michael Laudrup looking to bolster his defensive ranks ahead of a run of games that includes the Swans' UEFA Europa League and FA Cup with Budweiser campaigns.
Bartley initially signed for Blues on a season-long loan back in July
with the view to chalking up regular first-team football after an injury hit 2012/13.
The former Arsenal man has gone on to make 19 appearances, scoring five goals, in all competitions and formed a formidable centre-half partnership with Dan Burn during Blues' unbeaten run at the end of 2013.
As ever, bcfc.com will keep you updating with all developments as and when they happen.