The 19-year-old's previous contract at Fratton Park was due to expire at the end of the season.
Close made his debut for Pompey last term before going on to make a total of nine appearances for the team.
Portsmouth are back in action on Saturday when they travel to Plymouth Argyle in the league.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| C | Portsmouth | 45 | 27 | 13 | 5 | 76 | 41 | 35 | 94 |
| 2 | Derby CountyDerby | 45 | 27 | 8 | 10 | 76 | 37 | 39 | 89 |
| 3 | Bolton WanderersBolton | 45 | 25 | 11 | 9 | 83 | 48 | 35 | 86 |
| 4 | Peterborough UnitedPeterborough | 45 | 25 | 8 | 12 | 86 | 58 | 28 | 83 |
| 5 | Barnsley | 45 | 21 | 12 | 12 | 81 | 63 | 18 | 75 |
| 6 | Lincoln CityLincoln | 45 | 20 | 14 | 11 | 65 | 38 | 27 | 74 |
| 7 | Oxford UnitedOxford Utd | 45 | 21 | 11 | 13 | 77 | 55 | 22 | 74 |
| 8 | Blackpool | 45 | 21 | 10 | 14 | 63 | 45 | 18 | 73 |
| 9 | Stevenage | 45 | 18 | 14 | 13 | 55 | 45 | 10 | 68 |
| 10 | Wycombe WanderersWycombe | 45 | 16 | 14 | 15 | 59 | 55 | 4 | 62 |
| 11 | Leyton Orient | 45 | 17 | 11 | 17 | 50 | 54 | -4 | 62 |
| 12 | Exeter CityExeter | 45 | 17 | 10 | 18 | 45 | 59 | -14 | 61 |
| 13 | Wigan AthleticWigan | 45 | 19 | 10 | 16 | 61 | 56 | 5 | 59 |
| 14 | Northampton TownNorthampton | 45 | 17 | 8 | 20 | 56 | 65 | -9 | 59 |
| 15 | Bristol Rovers | 45 | 16 | 9 | 20 | 52 | 66 | -14 | 57 |
| 16 | Charlton AthleticCharlton | 45 | 11 | 20 | 14 | 64 | 64 | 0 | 53 |
| 17 | Reading | 45 | 15 | 11 | 19 | 65 | 68 | -3 | 50 |
| 18 | Shrewsbury TownShrewsbury | 45 | 13 | 9 | 23 | 34 | 64 | -30 | 48 |
| 19 | Cambridge UnitedCambridge | 45 | 12 | 11 | 22 | 39 | 61 | -22 | 47 |
| 20 | Burton Albion | 45 | 12 | 10 | 23 | 39 | 64 | -25 | 46 |
| 21 | Cheltenham TownCheltenham | 45 | 12 | 8 | 25 | 40 | 63 | -23 | 44 |
| R | Fleetwood TownFleetwood | 45 | 9 | 13 | 23 | 46 | 72 | -26 | 40 |
| R | Port Vale | 45 | 10 | 10 | 25 | 41 | 74 | -33 | 40 |
| R | Carlisle UnitedCarlisle | 45 | 7 | 9 | 29 | 41 | 79 | -38 | 30 |
| > League One Full Table | |||||||||
