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 | Wycombe WanderersWycombe | 16 | 12 | 2 | 2 | 36 | 18 | 18 | 38 |
| 2 | Wrexham | 17 | 10 | 4 | 3 | 26 | 11 | 15 | 34 |
| 3 | Birmingham CityBirmingham | 15 | 10 | 3 | 2 | 28 | 15 | 13 | 33 |
| 4 | Stockport CountyStockport | 17 | 8 | 6 | 3 | 29 | 17 | 12 | 30 |
| 5 | Huddersfield TownHuddersfield | 16 | 9 | 2 | 5 | 25 | 15 | 10 | 29 |
| 6 | Barnsley | 17 | 7 | 6 | 4 | 26 | 22 | 4 | 27 |
| 7 | Reading | 16 | 8 | 3 | 5 | 26 | 24 | 2 | 27 |
| 8 | Bolton WanderersBolton | 16 | 8 | 3 | 5 | 25 | 26 | -1 | 27 |
| 9 | Lincoln CityLincoln | 17 | 7 | 5 | 5 | 23 | 21 | 2 | 26 |
| 10 | Mansfield TownMansfield | 15 | 7 | 3 | 5 | 20 | 17 | 3 | 24 |
| 11 | Exeter CityExeter | 16 | 7 | 2 | 7 | 14 | 15 | -1 | 23 |
| 12 | Charlton AthleticCharlton | 16 | 6 | 4 | 6 | 17 | 17 | 0 | 22 |
| 13 | Peterborough UnitedPeterborough | 16 | 6 | 3 | 7 | 32 | 29 | 3 | 21 |
| 14 | Bristol Rovers | 17 | 6 | 3 | 8 | 17 | 23 | -6 | 21 |
| 15 | Wigan AthleticWigan | 16 | 5 | 5 | 6 | 15 | 13 | 2 | 20 |
| 16 | Blackpool | 17 | 5 | 5 | 7 | 24 | 30 | -6 | 20 |
| 17 | Stevenage | 16 | 5 | 4 | 7 | 11 | 16 | -5 | 19 |
| 18 | Northampton TownNorthampton | 17 | 4 | 6 | 7 | 19 | 23 | -4 | 18 |
| 19 | Rotherham UnitedRotherham | 16 | 4 | 5 | 7 | 14 | 19 | -5 | 17 |
| 20 | Crawley TownCrawley | 17 | 4 | 4 | 9 | 15 | 27 | -12 | 16 |
| 21 | Leyton Orient | 16 | 4 | 3 | 9 | 14 | 20 | -6 | 15 |
| 22 | Cambridge UnitedCambridge | 16 | 3 | 4 | 9 | 14 | 25 | -11 | 13 |
| 23 | Shrewsbury TownShrewsbury | 16 | 3 | 2 | 11 | 16 | 29 | -13 | 11 |
| 24 | Burton Albion | 16 | 1 | 5 | 10 | 15 | 29 | -14 | 8 |
| > League One Full Table | |||||||||
