The 23-year-old has penned a two-year contract with the League Two outfit.
Palmer spent the second half of last season on loan at Grimsby Town, scoring eight goals in 16 games for the non-league side.
Meanwhile, veteran forward Darius Henderson has left Orient following a one-year spell at Brisbane Road.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 19 | 13 | 4 | 2 | 43 | 22 | 21 | 43 |
| 2 | Birmingham CityBirmingham | 18 | 13 | 3 | 2 | 34 | 16 | 18 | 42 |
| 3 | Wrexham | 20 | 12 | 5 | 3 | 30 | 13 | 17 | 41 |
| 4 | Huddersfield TownHuddersfield | 19 | 11 | 3 | 5 | 30 | 18 | 12 | 36 |
| 5 | Stockport CountyStockport | 20 | 9 | 6 | 5 | 32 | 21 | 11 | 33 |
| 6 | Reading | 19 | 9 | 4 | 6 | 30 | 28 | 2 | 31 |
| 7 | Barnsley | 20 | 8 | 6 | 6 | 29 | 26 | 3 | 30 |
| 8 | Bolton WanderersBolton | 18 | 9 | 3 | 6 | 28 | 29 | -1 | 30 |
| 9 | Lincoln CityLincoln | 20 | 7 | 7 | 6 | 26 | 25 | 1 | 28 |
| 10 | Blackpool | 19 | 7 | 5 | 7 | 29 | 31 | -2 | 26 |
| 11 | Mansfield TownMansfield | 18 | 7 | 4 | 7 | 22 | 22 | 0 | 25 |
| 12 | Stevenage | 18 | 7 | 4 | 7 | 15 | 17 | -2 | 25 |
| 13 | Peterborough UnitedPeterborough | 19 | 7 | 3 | 9 | 37 | 35 | 2 | 24 |
| 14 | Charlton AthleticCharlton | 19 | 6 | 6 | 7 | 18 | 19 | -1 | 24 |
| 15 | Exeter CityExeter | 19 | 7 | 3 | 9 | 17 | 21 | -4 | 24 |
| 16 | Wigan AthleticWigan | 19 | 6 | 5 | 8 | 17 | 16 | 1 | 23 |
| 17 | Rotherham UnitedRotherham | 18 | 6 | 5 | 7 | 19 | 20 | -1 | 23 |
| 18 | Leyton Orient | 19 | 6 | 4 | 9 | 19 | 20 | -1 | 22 |
| 19 | Northampton TownNorthampton | 20 | 5 | 6 | 9 | 21 | 29 | -8 | 21 |
| 20 | Bristol Rovers | 19 | 6 | 3 | 10 | 17 | 28 | -11 | 21 |
| 21 | Crawley TownCrawley | 19 | 5 | 4 | 10 | 20 | 32 | -12 | 19 |
| 22 | Cambridge UnitedCambridge | 19 | 4 | 5 | 10 | 20 | 31 | -11 | 17 |
| 23 | Burton Albion | 19 | 2 | 6 | 11 | 16 | 30 | -14 | 12 |
| 24 | Shrewsbury TownShrewsbury | 19 | 3 | 2 | 14 | 19 | 39 | -20 | 11 |
| > League One Full Table | |||||||||
