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 | 3 | 3 | 0 | 0 | 7 | 0 | 7 | 9 |
| 2 | Watford | 3 | 3 | 0 | 0 | 8 | 3 | 5 | 9 |
| 3 | Blackburn RoversBlackburn | 3 | 2 | 1 | 0 | 8 | 5 | 3 | 7 |
| 4 | West Bromwich AlbionWest Brom | 3 | 2 | 1 | 0 | 5 | 2 | 3 | 7 |
| 5 | Burnley | 3 | 2 | 0 | 1 | 9 | 2 | 7 | 6 |
| 6 | Leeds UnitedLeeds | 3 | 1 | 2 | 0 | 5 | 3 | 2 | 5 |
| 7 | Bristol City | 3 | 1 | 2 | 0 | 6 | 5 | 1 | 5 |
| 8 | Coventry CityCoventry | 3 | 1 | 1 | 1 | 4 | 4 | 0 | 4 |
| 9 | Middlesbrough | 3 | 1 | 1 | 1 | 3 | 3 | 0 | 4 |
| 10 | Sheffield UnitedSheff Utd | 3 | 1 | 2 | 0 | 5 | 3 | 2 | 3 |
| 11 | Swansea CitySwansea | 2 | 1 | 0 | 1 | 3 | 1 | 2 | 3 |
| 12 | Oxford UnitedOxford Utd | 3 | 1 | 0 | 2 | 5 | 5 | 0 | 3 |
| 13 | Portsmouth | 3 | 0 | 3 | 0 | 5 | 5 | 0 | 3 |
| 14 | Hull City | 3 | 0 | 3 | 0 | 2 | 2 | 0 | 3 |
| 15 | Sheffield WednesdaySheff Weds | 3 | 1 | 0 | 2 | 4 | 6 | -2 | 3 |
| 16 | Derby CountyDerby | 3 | 1 | 0 | 2 | 4 | 6 | -2 | 3 |
| 17 | Stoke CityStoke | 3 | 1 | 0 | 2 | 2 | 5 | -3 | 3 |
| 18 | Preston North EndPreston | 3 | 1 | 0 | 2 | 1 | 5 | -4 | 3 |
| 19 | Queens Park RangersQPR | 3 | 0 | 2 | 1 | 4 | 6 | -2 | 2 |
| 20 | Norwich CityNorwich | 3 | 0 | 2 | 1 | 3 | 5 | -2 | 2 |
| 21 | Plymouth ArgylePlymouth | 3 | 0 | 2 | 1 | 2 | 6 | -4 | 2 |
| 22 | Millwall | 3 | 0 | 1 | 2 | 5 | 7 | -2 | 1 |
| 23 | Luton TownLuton | 3 | 0 | 1 | 2 | 1 | 5 | -4 | 1 |
| 24 | Cardiff CityCardiff | 2 | 0 | 0 | 2 | 0 | 7 | -7 | 0 |
| > Championship Full Table | |||||||||
