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 | Leicester CityLeicester | 44 | 30 | 4 | 10 | 86 | 39 | 47 | 94 |
| 2 | Leeds UnitedLeeds | 44 | 27 | 9 | 8 | 80 | 37 | 43 | 90 |
| 3 | Ipswich TownIpswich | 43 | 26 | 11 | 6 | 85 | 53 | 32 | 89 |
| 4 | Southampton | 44 | 25 | 9 | 10 | 85 | 61 | 24 | 84 |
| 5 | West Bromwich AlbionWest Brom | 44 | 20 | 12 | 12 | 67 | 44 | 23 | 72 |
| 6 | Norwich CityNorwich | 44 | 21 | 9 | 14 | 77 | 61 | 16 | 72 |
| 7 | Hull City | 44 | 19 | 12 | 13 | 65 | 56 | 9 | 69 |
| 8 | Coventry CityCoventry | 43 | 17 | 12 | 14 | 68 | 55 | 13 | 63 |
| 9 | Middlesbrough | 44 | 18 | 9 | 17 | 64 | 60 | 4 | 63 |
| 10 | Preston North EndPreston | 44 | 18 | 9 | 17 | 56 | 61 | -5 | 63 |
| 11 | Cardiff CityCardiff | 44 | 19 | 5 | 20 | 50 | 61 | -11 | 62 |
| 12 | Bristol City | 44 | 16 | 11 | 17 | 51 | 47 | 4 | 59 |
| 13 | Sunderland | 44 | 16 | 8 | 20 | 52 | 51 | 1 | 56 |
| 14 | Swansea CitySwansea | 44 | 15 | 11 | 18 | 57 | 62 | -5 | 56 |
| 15 | Watford | 44 | 12 | 17 | 15 | 59 | 58 | 1 | 53 |
| 16 | Millwall | 44 | 14 | 11 | 19 | 43 | 55 | -12 | 53 |
| 17 | Stoke CityStoke | 44 | 13 | 11 | 20 | 44 | 60 | -16 | 50 |
| 18 | Queens Park RangersQPR | 44 | 13 | 11 | 20 | 41 | 57 | -16 | 50 |
| 19 | Blackburn RoversBlackburn | 44 | 13 | 10 | 21 | 58 | 74 | -16 | 49 |
| 20 | Plymouth ArgylePlymouth | 44 | 12 | 12 | 20 | 58 | 69 | -11 | 48 |
| 21 | Sheffield WednesdaySheff Weds | 44 | 13 | 8 | 23 | 39 | 68 | -29 | 47 |
| 22 | Birmingham CityBirmingham | 44 | 12 | 10 | 22 | 48 | 64 | -16 | 46 |
| 23 | Huddersfield TownHuddersfield | 44 | 9 | 17 | 18 | 47 | 74 | -27 | 44 |
| R | Rotherham UnitedRotherham | 44 | 4 | 12 | 28 | 32 | 85 | -53 | 24 |
| > Championship Full Table | |||||||||
