The Sydney-born 19-year-old has made the switch to Loftus Road from Palm Beach Soccer Club in his native Australia.
According to the Championship club's official website, Wallen will initially link up with the development squad in West London.
The youngster, who was previously on the books of Premier League side Watford, has agreed a contract until June 2017.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Sunderland | 9 | 6 | 1 | 2 | 18 | 8 | 10 | 19 |
| 2 | Sheffield UnitedSheff Utd | 9 | 6 | 3 | 0 | 12 | 3 | 9 | 19 |
| 3 | Burnley | 9 | 5 | 3 | 1 | 14 | 4 | 10 | 18 |
| 4 | West Bromwich AlbionWest Brom | 9 | 5 | 2 | 2 | 12 | 6 | 6 | 17 |
| 5 | Leeds UnitedLeeds | 9 | 4 | 4 | 1 | 15 | 7 | 8 | 16 |
| 6 | Watford | 9 | 5 | 1 | 3 | 14 | 14 | 0 | 16 |
| 7 | Norwich CityNorwich | 9 | 4 | 3 | 2 | 16 | 10 | 6 | 15 |
| 8 | Blackburn RoversBlackburn | 9 | 4 | 3 | 2 | 15 | 11 | 4 | 15 |
| 9 | Middlesbrough | 9 | 4 | 2 | 3 | 10 | 7 | 3 | 14 |
| 10 | Oxford UnitedOxford Utd | 9 | 3 | 3 | 3 | 13 | 11 | 2 | 12 |
| 11 | Swansea CitySwansea | 9 | 3 | 3 | 3 | 8 | 6 | 2 | 12 |
| 12 | Derby CountyDerby | 9 | 4 | 0 | 5 | 12 | 12 | 0 | 12 |
| 13 | Hull City | 9 | 3 | 3 | 3 | 12 | 13 | -1 | 12 |
| 14 | Plymouth ArgylePlymouth | 9 | 3 | 2 | 4 | 10 | 13 | -3 | 11 |
| 15 | Sheffield WednesdaySheff Weds | 9 | 3 | 2 | 4 | 11 | 15 | -4 | 11 |
| 16 | Stoke CityStoke | 9 | 3 | 1 | 5 | 10 | 12 | -2 | 10 |
| 17 | Bristol City | 8 | 2 | 4 | 2 | 9 | 13 | -4 | 10 |
| 18 | Millwall | 9 | 2 | 3 | 4 | 12 | 11 | 1 | 9 |
| 19 | Preston North EndPreston | 9 | 2 | 3 | 4 | 7 | 12 | -5 | 9 |
| 20 | Coventry CityCoventry | 9 | 2 | 2 | 5 | 10 | 13 | -3 | 8 |
| 21 | Luton TownLuton | 9 | 2 | 2 | 5 | 8 | 15 | -7 | 8 |
| 22 | Queens Park RangersQPR | 9 | 1 | 4 | 4 | 9 | 16 | -7 | 7 |
| 23 | Portsmouth | 9 | 0 | 5 | 4 | 9 | 20 | -11 | 5 |
| 24 | Cardiff CityCardiff | 8 | 1 | 1 | 6 | 3 | 17 | -14 | 4 |
| > Championship Full Table | |||||||||
