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 | Wrexham | 6 | 4 | 1 | 1 | 12 | 5 | 7 | 13 |
| 2 | Birmingham CityBirmingham | 5 | 4 | 1 | 0 | 11 | 6 | 5 | 13 |
| 3 | Charlton AthleticCharlton | 6 | 4 | 1 | 1 | 6 | 3 | 3 | 13 |
| 4 | Huddersfield TownHuddersfield | 5 | 4 | 0 | 1 | 10 | 3 | 7 | 12 |
| 5 | Stockport CountyStockport | 5 | 3 | 2 | 0 | 9 | 2 | 7 | 11 |
| 6 | Lincoln CityLincoln | 5 | 3 | 1 | 1 | 10 | 6 | 4 | 10 |
| 7 | Barnsley | 6 | 3 | 1 | 2 | 10 | 9 | 1 | 10 |
| 8 | Mansfield TownMansfield | 5 | 2 | 2 | 1 | 9 | 10 | -1 | 8 |
| 9 | Stevenage | 5 | 2 | 1 | 2 | 5 | 3 | 2 | 7 |
| 10 | Wycombe WanderersWycombe | 5 | 2 | 1 | 2 | 10 | 9 | 1 | 7 |
| 11 | Peterborough UnitedPeterborough | 5 | 2 | 1 | 2 | 7 | 7 | 0 | 7 |
| 12 | Reading | 5 | 2 | 1 | 2 | 5 | 5 | 0 | 7 |
| 13 | Crawley TownCrawley | 5 | 2 | 1 | 2 | 4 | 6 | -2 | 7 |
| 14 | Bristol Rovers | 6 | 2 | 1 | 3 | 4 | 8 | -4 | 7 |
| 15 | Wigan AthleticWigan | 5 | 2 | 0 | 3 | 6 | 5 | 1 | 6 |
| 16 | Exeter CityExeter | 5 | 2 | 0 | 3 | 6 | 6 | 0 | 6 |
| 17 | Rotherham UnitedRotherham | 6 | 1 | 3 | 2 | 5 | 7 | -2 | 6 |
| 18 | Northampton TownNorthampton | 5 | 1 | 2 | 2 | 5 | 6 | -1 | 5 |
| 19 | Blackpool | 5 | 1 | 2 | 2 | 9 | 12 | -3 | 5 |
| 20 | Burton Albion | 5 | 0 | 4 | 1 | 7 | 8 | -1 | 4 |
| 21 | Bolton WanderersBolton | 5 | 1 | 1 | 3 | 2 | 9 | -7 | 4 |
| 22 | Leyton Orient | 5 | 1 | 0 | 4 | 3 | 8 | -5 | 3 |
| 23 | Shrewsbury TownShrewsbury | 6 | 1 | 0 | 5 | 4 | 10 | -6 | 3 |
| 24 | Cambridge UnitedCambridge | 5 | 0 | 1 | 4 | 5 | 11 | -6 | 1 |
| > League One Full Table | |||||||||
