The 34-year-old frontman joins the Robins following his release from Premier League side Crystal Palace.
"Aaron is a top lad and a top professional," City boss Steve Cotterill told the club website.
"He's certainly a physical presence up top and that's what we need in the squad."
Wilbraham made just one start for Palace in the top flight last season.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Sheffield UnitedSheff Utd | 21 | 14 | 5 | 2 | 30 | 11 | 19 | 45 |
| 2 | Leeds UnitedLeeds | 21 | 12 | 6 | 3 | 37 | 15 | 22 | 42 |
| 3 | Sunderland | 21 | 11 | 7 | 3 | 32 | 17 | 15 | 40 |
| 4 | Burnley | 20 | 10 | 8 | 2 | 24 | 7 | 17 | 38 |
| 5 | Blackburn RoversBlackburn | 20 | 11 | 4 | 5 | 25 | 17 | 8 | 37 |
| 6 | Middlesbrough | 21 | 10 | 4 | 7 | 35 | 25 | 10 | 34 |
| 7 | West Bromwich AlbionWest Brom | 20 | 7 | 11 | 2 | 23 | 14 | 9 | 32 |
| 8 | Watford | 19 | 9 | 4 | 6 | 27 | 25 | 2 | 31 |
| 9 | Sheffield WednesdaySheff Weds | 21 | 8 | 5 | 8 | 26 | 30 | -4 | 29 |
| 10 | Swansea CitySwansea | 21 | 7 | 6 | 8 | 23 | 22 | 1 | 27 |
| 11 | Bristol City | 21 | 6 | 9 | 6 | 26 | 26 | 0 | 27 |
| 12 | Norwich CityNorwich | 20 | 6 | 8 | 6 | 35 | 30 | 5 | 26 |
| 13 | Millwall | 20 | 6 | 7 | 7 | 20 | 18 | 2 | 25 |
| 14 | Derby CountyDerby | 21 | 6 | 6 | 9 | 26 | 26 | 0 | 24 |
| 15 | Coventry CityCoventry | 21 | 6 | 6 | 9 | 27 | 30 | -3 | 24 |
| 16 | Preston North EndPreston | 21 | 4 | 11 | 6 | 21 | 27 | -6 | 23 |
| 17 | Stoke CityStoke | 21 | 5 | 7 | 9 | 23 | 28 | -5 | 22 |
| 18 | Queens Park RangersQPR | 21 | 4 | 10 | 7 | 21 | 27 | -6 | 22 |
| 19 | Luton TownLuton | 21 | 6 | 4 | 11 | 23 | 37 | -14 | 22 |
| 20 | Oxford UnitedOxford Utd | 20 | 4 | 6 | 10 | 21 | 33 | -12 | 18 |
| 21 | Cardiff CityCardiff | 20 | 4 | 6 | 10 | 19 | 32 | -13 | 18 |
| 22 | Portsmouth | 19 | 3 | 8 | 8 | 21 | 34 | -13 | 17 |
| 23 | Plymouth ArgylePlymouth | 20 | 4 | 5 | 11 | 19 | 42 | -23 | 17 |
| 24 | Hull City | 21 | 3 | 7 | 11 | 19 | 30 | -11 | 16 |
| > Championship Full Table | |||||||||
