The Belgian forward, 25, joins the Championship side from Genk in his homeland.
In the last four seasons for Genk he has found the net on 69 occasions in the Belgian Pro League. At senior level for Belgium, he has two goals in 12 appearances.
Vossen is Boro's second signing of deadline day after they added Dutch winger Yanic Wildschut.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Sunderland | 9 | 6 | 1 | 2 | 18 | 8 | 10 | 19 |
| 2 | Burnley | 8 | 5 | 2 | 1 | 14 | 4 | 10 | 17 |
| 3 | Leeds UnitedLeeds | 9 | 4 | 4 | 1 | 15 | 7 | 8 | 16 |
| 4 | Sheffield UnitedSheff Utd | 8 | 5 | 3 | 0 | 10 | 3 | 7 | 16 |
| 5 | West Bromwich AlbionWest Brom | 8 | 5 | 1 | 2 | 12 | 6 | 6 | 16 |
| 6 | Blackburn RoversBlackburn | 8 | 4 | 3 | 1 | 14 | 9 | 5 | 15 |
| 7 | Middlesbrough | 8 | 4 | 2 | 2 | 9 | 5 | 4 | 14 |
| 8 | Watford | 8 | 4 | 1 | 3 | 12 | 13 | -1 | 13 |
| 9 | Hull City | 8 | 3 | 3 | 2 | 12 | 9 | 3 | 12 |
| 10 | Norwich CityNorwich | 8 | 3 | 3 | 2 | 12 | 10 | 2 | 12 |
| 11 | Oxford UnitedOxford Utd | 8 | 3 | 2 | 3 | 12 | 10 | 2 | 11 |
| 12 | Swansea CitySwansea | 8 | 3 | 2 | 3 | 8 | 6 | 2 | 11 |
| 13 | Bristol City | 8 | 2 | 4 | 2 | 9 | 13 | -4 | 10 |
| 14 | Stoke CityStoke | 8 | 3 | 0 | 5 | 10 | 12 | -2 | 9 |
| 15 | Derby CountyDerby | 8 | 3 | 0 | 5 | 10 | 12 | -2 | 9 |
| 16 | Millwall | 8 | 2 | 2 | 4 | 12 | 11 | 1 | 8 |
| 17 | Coventry CityCoventry | 8 | 2 | 2 | 4 | 9 | 11 | -2 | 8 |
| 18 | Plymouth ArgylePlymouth | 8 | 2 | 2 | 4 | 8 | 12 | -4 | 8 |
| 19 | Sheffield WednesdaySheff Weds | 8 | 2 | 2 | 4 | 9 | 14 | -5 | 8 |
| 20 | Luton TownLuton | 8 | 2 | 2 | 4 | 8 | 13 | -5 | 8 |
| 21 | Preston North EndPreston | 8 | 2 | 2 | 4 | 7 | 12 | -5 | 8 |
| 22 | Queens Park RangersQPR | 8 | 1 | 4 | 3 | 9 | 14 | -5 | 7 |
| 23 | Portsmouth | 8 | 0 | 4 | 4 | 8 | 19 | -11 | 4 |
| 24 | Cardiff CityCardiff | 8 | 1 | 1 | 6 | 3 | 17 | -14 | 4 |
| > Championship Full Table | |||||||||
