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 | 14 | 10 | 2 | 2 | 32 | 16 | 16 | 32 |
| 2 | Birmingham CityBirmingham | 13 | 9 | 3 | 1 | 24 | 12 | 12 | 30 |
| 3 | Wrexham | 15 | 8 | 4 | 3 | 22 | 11 | 11 | 28 |
| 4 | Stockport CountyStockport | 16 | 7 | 6 | 3 | 26 | 17 | 9 | 27 |
| 5 | Barnsley | 15 | 7 | 5 | 3 | 24 | 19 | 5 | 26 |
| 6 | Lincoln CityLincoln | 15 | 7 | 5 | 3 | 21 | 17 | 4 | 26 |
| 7 | Mansfield TownMansfield | 13 | 7 | 3 | 3 | 20 | 15 | 5 | 24 |
| 8 | Huddersfield TownHuddersfield | 14 | 7 | 2 | 5 | 21 | 14 | 7 | 23 |
| 9 | Exeter CityExeter | 14 | 7 | 2 | 5 | 14 | 10 | 4 | 23 |
| 10 | Reading | 14 | 7 | 2 | 5 | 22 | 21 | 1 | 23 |
| 11 | Bolton WanderersBolton | 14 | 7 | 2 | 5 | 22 | 24 | -2 | 23 |
| 12 | Peterborough UnitedPeterborough | 15 | 6 | 3 | 6 | 31 | 27 | 4 | 21 |
| 13 | Charlton AthleticCharlton | 14 | 5 | 4 | 5 | 15 | 15 | 0 | 19 |
| 14 | Bristol Rovers | 15 | 5 | 3 | 7 | 16 | 21 | -5 | 18 |
| 15 | Stevenage | 15 | 5 | 3 | 7 | 11 | 16 | -5 | 18 |
| 16 | Northampton TownNorthampton | 15 | 4 | 5 | 6 | 18 | 21 | -3 | 17 |
| 17 | Rotherham UnitedRotherham | 15 | 4 | 5 | 6 | 14 | 18 | -4 | 17 |
| 18 | Blackpool | 15 | 4 | 5 | 6 | 21 | 28 | -7 | 17 |
| 19 | Wigan AthleticWigan | 14 | 3 | 5 | 6 | 12 | 12 | 0 | 14 |
| 20 | Leyton Orient | 14 | 4 | 2 | 8 | 14 | 18 | -4 | 14 |
| 21 | Crawley TownCrawley | 16 | 3 | 4 | 9 | 14 | 27 | -13 | 13 |
| 22 | Cambridge UnitedCambridge | 14 | 3 | 2 | 9 | 13 | 24 | -11 | 11 |
| 23 | Burton Albion | 14 | 1 | 5 | 8 | 15 | 25 | -10 | 8 |
| 24 | Shrewsbury TownShrewsbury | 15 | 2 | 2 | 11 | 13 | 27 | -14 | 8 |
| > League One Full Table | |||||||||
