The 27-year-old striker moves back to St Andrew's until the end of the season having made six appearances in a recent loan spell.
As part of the deal, Birmingham will also make the move permanent at the end of the campaign.
Vaughan did not score in his recent stint with the Blues, but did set up their winner against Brentford last Saturday.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 14 | 10 | 2 | 2 | 32 | 16 | 16 | 32 |
| 2 | Birmingham CityBirmingham | 13 | 9 | 3 | 1 | 24 | 12 | 12 | 30 |
| 3 | Wrexham | 14 | 8 | 4 | 2 | 22 | 10 | 12 | 28 |
| 4 | Barnsley | 14 | 7 | 4 | 3 | 23 | 18 | 5 | 25 |
| 5 | Lincoln CityLincoln | 14 | 7 | 4 | 3 | 21 | 17 | 4 | 25 |
| 6 | Stockport CountyStockport | 15 | 6 | 6 | 3 | 25 | 17 | 8 | 24 |
| 7 | Mansfield TownMansfield | 13 | 7 | 3 | 3 | 20 | 15 | 5 | 24 |
| 8 | Huddersfield TownHuddersfield | 14 | 7 | 2 | 5 | 21 | 14 | 7 | 23 |
| 9 | Reading | 14 | 7 | 2 | 5 | 22 | 21 | 1 | 23 |
| 10 | Bolton WanderersBolton | 14 | 7 | 2 | 5 | 22 | 24 | -2 | 23 |
| 11 | Exeter CityExeter | 13 | 7 | 1 | 5 | 14 | 10 | 4 | 22 |
| 12 | Peterborough UnitedPeterborough | 15 | 6 | 3 | 6 | 31 | 27 | 4 | 21 |
| 13 | Charlton AthleticCharlton | 14 | 5 | 4 | 5 | 15 | 15 | 0 | 19 |
| 14 | Stevenage | 15 | 5 | 3 | 7 | 11 | 16 | -5 | 18 |
| 15 | Rotherham UnitedRotherham | 15 | 4 | 5 | 6 | 14 | 18 | -4 | 17 |
| 16 | Bristol Rovers | 14 | 5 | 2 | 7 | 16 | 21 | -5 | 17 |
| 17 | Northampton TownNorthampton | 14 | 4 | 4 | 6 | 18 | 21 | -3 | 16 |
| 18 | Blackpool | 14 | 4 | 4 | 6 | 21 | 28 | -7 | 16 |
| 19 | Wigan AthleticWigan | 14 | 3 | 5 | 6 | 12 | 12 | 0 | 14 |
| 20 | Leyton Orient | 14 | 4 | 2 | 8 | 14 | 18 | -4 | 14 |
| 21 | Crawley TownCrawley | 15 | 3 | 3 | 9 | 14 | 27 | -13 | 12 |
| 22 | Cambridge UnitedCambridge | 13 | 3 | 1 | 9 | 12 | 23 | -11 | 10 |
| 23 | Burton Albion | 14 | 1 | 5 | 8 | 15 | 25 | -10 | 8 |
| 24 | Shrewsbury TownShrewsbury | 15 | 2 | 2 | 11 | 13 | 27 | -14 | 8 |
| > League One Full Table | |||||||||
