The loan, which started today, runs up to and including Saturday 1 March. Blues have included a 28-day recall within the agreement if required.
The midfielder goes straight into the Robins' squad for this evening's league trip to Brentford.
So far this season, the 35-year-old has made 11 starts and seven substitute appearances for Blues, but more recently has faced stiff competition for a place in the centre of the park.
Bristol City, who are managed by Steve Cotterill, are currently struggling in 23rd place in League One, just two points ahead of basement side Stevenage.
They have not won a league game since beating Stevenage 4-1 on 29 December.