The 27-year-old has signed a two-year deal at Bloomfield Road.
Robertson has played in Scotland throughout his career, starting at Dundee before moving to rivals United in 2008.
The Scottish international becomes Ian Holloway's fourth summer signing after the arrivals of Tiago Gomes, Isaiah Osbourne and Jake Caprice.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 18 | 12 | 4 | 2 | 39 | 21 | 18 | 40 |
| 2 | Wrexham | 19 | 12 | 4 | 3 | 28 | 11 | 17 | 40 |
| 3 | Birmingham CityBirmingham | 17 | 12 | 3 | 2 | 32 | 16 | 16 | 39 |
| 4 | Huddersfield TownHuddersfield | 18 | 11 | 2 | 5 | 28 | 16 | 12 | 35 |
| 5 | Stockport CountyStockport | 19 | 9 | 6 | 4 | 31 | 19 | 12 | 33 |
| 6 | Reading | 18 | 9 | 4 | 5 | 30 | 25 | 5 | 31 |
| 7 | Bolton WanderersBolton | 17 | 9 | 3 | 5 | 28 | 27 | 1 | 30 |
| 8 | Barnsley | 19 | 7 | 6 | 6 | 27 | 25 | 2 | 27 |
| 9 | Lincoln CityLincoln | 19 | 7 | 6 | 6 | 24 | 23 | 1 | 27 |
| 10 | Mansfield TownMansfield | 17 | 7 | 3 | 7 | 22 | 22 | 0 | 24 |
| 11 | Exeter CityExeter | 18 | 7 | 3 | 8 | 16 | 19 | -3 | 24 |
| 12 | Charlton AthleticCharlton | 18 | 6 | 5 | 7 | 18 | 19 | -1 | 23 |
| 13 | Blackpool | 18 | 6 | 5 | 7 | 26 | 31 | -5 | 23 |
| 14 | Stevenage | 17 | 6 | 4 | 7 | 13 | 16 | -3 | 22 |
| 15 | Peterborough UnitedPeterborough | 18 | 6 | 3 | 9 | 33 | 32 | 1 | 21 |
| 16 | Leyton Orient | 18 | 6 | 3 | 9 | 19 | 20 | -1 | 21 |
| 17 | Northampton TownNorthampton | 19 | 5 | 6 | 8 | 21 | 26 | -5 | 21 |
| 18 | Bristol Rovers | 18 | 6 | 3 | 9 | 17 | 26 | -9 | 21 |
| 19 | Wigan AthleticWigan | 18 | 5 | 5 | 8 | 15 | 16 | -1 | 20 |
| 20 | Rotherham UnitedRotherham | 17 | 5 | 5 | 7 | 16 | 20 | -4 | 20 |
| 21 | Crawley TownCrawley | 18 | 5 | 4 | 9 | 17 | 28 | -11 | 19 |
| 22 | Cambridge UnitedCambridge | 18 | 4 | 4 | 10 | 18 | 29 | -11 | 16 |
| 23 | Burton Albion | 18 | 2 | 5 | 11 | 16 | 30 | -14 | 11 |
| 24 | Shrewsbury TownShrewsbury | 18 | 3 | 2 | 13 | 18 | 35 | -17 | 11 |
| > League One Full Table | |||||||||
