The 24-year-old will stay with the Blues until the end of the season, but an option is in place for Watford to recall their player after 28 days.
Fabbrini, who signed for Watford from Udinese in 2013, provides versatility for Birmingham boss Gary Rowett as he can play as a right-winger, midfielder or second striker.
The Italian has had loan spells at Siena and Millwall during his time at Watford.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 15 | 11 | 2 | 2 | 35 | 18 | 17 | 35 |
| 2 | Wrexham | 16 | 9 | 4 | 3 | 25 | 11 | 14 | 31 |
| 3 | Stockport CountyStockport | 17 | 8 | 6 | 3 | 29 | 17 | 12 | 30 |
| 4 | Birmingham CityBirmingham | 14 | 9 | 3 | 2 | 26 | 15 | 11 | 30 |
| 5 | Huddersfield TownHuddersfield | 15 | 8 | 2 | 5 | 23 | 15 | 8 | 26 |
| 6 | Barnsley | 16 | 7 | 5 | 4 | 24 | 20 | 4 | 26 |
| 7 | Lincoln CityLincoln | 16 | 7 | 5 | 4 | 23 | 20 | 3 | 26 |
| 8 | Reading | 15 | 8 | 2 | 5 | 24 | 22 | 2 | 26 |
| 9 | Bolton WanderersBolton | 15 | 8 | 2 | 5 | 24 | 25 | -1 | 26 |
| 10 | Mansfield TownMansfield | 14 | 7 | 3 | 4 | 20 | 16 | 4 | 24 |
| 11 | Exeter CityExeter | 15 | 7 | 2 | 6 | 14 | 13 | 1 | 23 |
| 12 | Peterborough UnitedPeterborough | 16 | 6 | 3 | 7 | 32 | 29 | 3 | 21 |
| 13 | Bristol Rovers | 16 | 6 | 3 | 7 | 17 | 21 | -4 | 21 |
| 14 | Charlton AthleticCharlton | 15 | 5 | 4 | 6 | 16 | 17 | -1 | 19 |
| 15 | Stevenage | 16 | 5 | 4 | 7 | 11 | 16 | -5 | 19 |
| 16 | Northampton TownNorthampton | 16 | 4 | 6 | 6 | 18 | 21 | -3 | 18 |
| 17 | Wigan AthleticWigan | 15 | 4 | 5 | 6 | 13 | 12 | 1 | 17 |
| 18 | Rotherham UnitedRotherham | 16 | 4 | 5 | 7 | 14 | 19 | -5 | 17 |
| 19 | Blackpool | 16 | 4 | 5 | 7 | 22 | 30 | -8 | 17 |
| 20 | Crawley TownCrawley | 17 | 4 | 4 | 9 | 15 | 27 | -12 | 16 |
| 21 | Leyton Orient | 15 | 4 | 3 | 8 | 14 | 18 | -4 | 15 |
| 22 | Cambridge UnitedCambridge | 15 | 3 | 3 | 9 | 13 | 24 | -11 | 12 |
| 23 | Shrewsbury TownShrewsbury | 16 | 3 | 2 | 11 | 16 | 29 | -13 | 11 |
| 24 | Burton Albion | 15 | 1 | 5 | 9 | 15 | 28 | -13 | 8 |
| > League One Full Table | |||||||||
