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 | 23 | 15 | 5 | 3 | 49 | 25 | 24 | 50 |
| 2 | Birmingham CityBirmingham | 22 | 15 | 5 | 2 | 38 | 17 | 21 | 50 |
| 3 | Wrexham | 24 | 14 | 6 | 4 | 36 | 18 | 18 | 48 |
| 4 | Huddersfield TownHuddersfield | 22 | 13 | 4 | 5 | 36 | 19 | 17 | 43 |
| 5 | Reading | 23 | 12 | 4 | 7 | 39 | 33 | 6 | 40 |
| 6 | Barnsley | 24 | 11 | 6 | 7 | 36 | 33 | 3 | 39 |
| 7 | Stockport CountyStockport | 24 | 10 | 8 | 6 | 36 | 25 | 11 | 38 |
| 8 | Leyton Orient | 23 | 10 | 4 | 9 | 31 | 22 | 9 | 34 |
| 9 | Mansfield TownMansfield | 22 | 10 | 4 | 8 | 29 | 25 | 4 | 34 |
| 10 | Bolton WanderersBolton | 22 | 10 | 4 | 8 | 33 | 33 | 0 | 34 |
| 11 | Charlton AthleticCharlton | 22 | 9 | 6 | 7 | 27 | 21 | 6 | 33 |
| 12 | Lincoln CityLincoln | 24 | 8 | 7 | 9 | 28 | 30 | -2 | 31 |
| 13 | Exeter CityExeter | 23 | 9 | 4 | 10 | 27 | 29 | -2 | 31 |
| 14 | Stevenage | 22 | 8 | 6 | 8 | 18 | 20 | -2 | 30 |
| 15 | Blackpool | 23 | 7 | 8 | 8 | 31 | 34 | -3 | 29 |
| 16 | Wigan AthleticWigan | 22 | 7 | 6 | 9 | 21 | 20 | 1 | 27 |
| 17 | Rotherham UnitedRotherham | 22 | 7 | 6 | 9 | 21 | 23 | -2 | 27 |
| 18 | Peterborough UnitedPeterborough | 23 | 7 | 4 | 12 | 41 | 45 | -4 | 25 |
| 19 | Northampton TownNorthampton | 24 | 5 | 8 | 11 | 23 | 39 | -16 | 23 |
| 20 | Bristol Rovers | 23 | 6 | 4 | 13 | 21 | 38 | -17 | 22 |
| 21 | Crawley TownCrawley | 22 | 5 | 5 | 12 | 24 | 40 | -16 | 20 |
| 22 | Shrewsbury TownShrewsbury | 23 | 4 | 5 | 14 | 24 | 43 | -19 | 17 |
| 23 | Cambridge UnitedCambridge | 23 | 4 | 5 | 14 | 22 | 42 | -20 | 17 |
| 24 | Burton Albion | 23 | 2 | 8 | 13 | 20 | 37 | -17 | 14 |
| > League One Full Table | |||||||||
