The 34-year-old arrives as a free agent following his release from Bloomfield Road at the end of last season.
Fuller scored six goals in 28 appearances for Blackpool after moving to the club from Charlton Athletic in August 2013.
The veteran forward is Ian Holloway's fourth signing of the summer at The Den.
Millwall start their Championship campaign at home to Leeds United on August 9.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Sheffield UnitedSheff Utd | 17 | 11 | 4 | 2 | 24 | 9 | 15 | 35 |
| 2 | Burnley | 17 | 9 | 6 | 2 | 21 | 6 | 15 | 33 |
| 3 | Sunderland | 17 | 9 | 6 | 2 | 26 | 12 | 14 | 33 |
| 4 | Leeds UnitedLeeds | 16 | 9 | 5 | 2 | 28 | 12 | 16 | 32 |
| 5 | Watford | 17 | 9 | 2 | 6 | 26 | 24 | 2 | 29 |
| 6 | Middlesbrough | 16 | 8 | 3 | 5 | 29 | 19 | 10 | 27 |
| 7 | West Bromwich AlbionWest Brom | 17 | 6 | 9 | 2 | 18 | 11 | 7 | 27 |
| 8 | Millwall | 16 | 6 | 6 | 4 | 19 | 14 | 5 | 24 |
| 9 | Norwich CityNorwich | 17 | 5 | 7 | 5 | 31 | 25 | 6 | 22 |
| 10 | Blackburn RoversBlackburn | 15 | 6 | 4 | 5 | 19 | 17 | 2 | 22 |
| 11 | Bristol City | 17 | 5 | 7 | 5 | 20 | 21 | -1 | 22 |
| 12 | Sheffield WednesdaySheff Weds | 17 | 6 | 4 | 7 | 20 | 26 | -6 | 22 |
| 13 | Stoke CityStoke | 17 | 5 | 6 | 6 | 19 | 20 | -1 | 21 |
| 14 | Derby CountyDerby | 16 | 5 | 5 | 6 | 20 | 20 | 0 | 20 |
| 15 | Swansea CitySwansea | 16 | 5 | 4 | 7 | 14 | 14 | 0 | 19 |
| 16 | Luton TownLuton | 16 | 5 | 3 | 8 | 18 | 26 | -8 | 18 |
| 17 | Coventry CityCoventry | 17 | 4 | 5 | 8 | 22 | 25 | -3 | 17 |
| 18 | Oxford UnitedOxford Utd | 17 | 4 | 5 | 8 | 19 | 27 | -8 | 17 |
| 19 | Preston North EndPreston | 17 | 3 | 8 | 6 | 16 | 24 | -8 | 17 |
| 20 | Plymouth ArgylePlymouth | 17 | 4 | 5 | 8 | 18 | 34 | -16 | 17 |
| 21 | Cardiff CityCardiff | 16 | 4 | 4 | 8 | 15 | 24 | -9 | 16 |
| 22 | Hull City | 17 | 3 | 6 | 8 | 16 | 23 | -7 | 15 |
| 23 | Portsmouth | 15 | 2 | 6 | 7 | 16 | 28 | -12 | 12 |
| 24 | Queens Park RangersQPR | 16 | 1 | 8 | 7 | 13 | 26 | -13 | 11 |
| > Championship Full Table | |||||||||
