The 26-year-old's previous deal had been due to expire at the end of next season.
However, under the terms of the new commitment, Cox has tied himself to the Matchroom Stadium until the summer of 2017.
Cox, who joined Orient from Brighton & Hove Albion in 2010, scored 17 goals in his 56 appearances in all competitions last term.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Birmingham CityBirmingham | 27 | 19 | 6 | 2 | 46 | 19 | 27 | 63 |
| 2 | Wycombe WanderersWycombe | 29 | 17 | 8 | 4 | 55 | 30 | 25 | 59 |
| 3 | Wrexham | 29 | 16 | 7 | 6 | 43 | 25 | 18 | 55 |
| 4 | Stockport CountyStockport | 29 | 14 | 8 | 7 | 44 | 28 | 16 | 50 |
| 5 | Huddersfield TownHuddersfield | 28 | 14 | 6 | 8 | 41 | 26 | 15 | 48 |
| 6 | Leyton Orient | 28 | 13 | 5 | 10 | 40 | 25 | 15 | 44 |
| 7 | Charlton AthleticCharlton | 28 | 12 | 8 | 8 | 36 | 28 | 8 | 44 |
| 8 | Reading | 28 | 13 | 5 | 10 | 43 | 41 | 2 | 44 |
| 9 | Bolton WanderersBolton | 29 | 13 | 5 | 11 | 43 | 43 | 0 | 44 |
| 10 | Barnsley | 29 | 12 | 7 | 10 | 41 | 39 | 2 | 43 |
| 11 | Stevenage | 27 | 11 | 7 | 9 | 27 | 25 | 2 | 40 |
| 12 | Lincoln CityLincoln | 29 | 10 | 9 | 10 | 35 | 34 | 1 | 39 |
| 13 | Blackpool | 28 | 9 | 11 | 8 | 41 | 40 | 1 | 38 |
| 14 | Mansfield TownMansfield | 27 | 11 | 4 | 12 | 35 | 34 | 1 | 37 |
| 15 | Rotherham UnitedRotherham | 28 | 10 | 7 | 11 | 33 | 33 | 0 | 37 |
| 16 | Wigan AthleticWigan | 28 | 9 | 7 | 12 | 27 | 28 | -1 | 34 |
| 17 | Exeter CityExeter | 29 | 9 | 5 | 15 | 33 | 46 | -13 | 32 |
| 18 | Peterborough UnitedPeterborough | 28 | 8 | 6 | 14 | 44 | 52 | -8 | 30 |
| 19 | Northampton TownNorthampton | 29 | 7 | 9 | 13 | 28 | 45 | -17 | 30 |
| 20 | Bristol Rovers | 27 | 8 | 4 | 15 | 25 | 43 | -18 | 28 |
| 21 | Burton Albion | 29 | 5 | 10 | 14 | 30 | 44 | -14 | 25 |
| 22 | Crawley TownCrawley | 27 | 6 | 6 | 15 | 27 | 48 | -21 | 24 |
| 23 | Shrewsbury TownShrewsbury | 28 | 6 | 5 | 17 | 28 | 48 | -20 | 23 |
| 24 | Cambridge UnitedCambridge | 28 | 5 | 7 | 16 | 29 | 50 | -21 | 22 |
| > League One Full Table | |||||||||
