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