The 22-year-old moves North to the Reebok two weeks after his initial loan move to Wanderers fell through after talks between managers Malky Mackay and Dougie Freedman.
Striker Mason joins fellow Cardiff player Kevin McNaughton at Bolton, who are 15th in the table after a recent run of eight games unbeaten.
He could make his first appearance for the club at Middlesbrough this weekend.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| C | Portsmouth | 46 | 28 | 13 | 5 | 78 | 41 | 37 | 97 |
| P | Derby CountyDerby | 46 | 28 | 8 | 10 | 78 | 37 | 41 | 92 |
| 3 | Bolton WanderersBolton | 46 | 25 | 12 | 9 | 86 | 51 | 35 | 87 |
| 4 | Peterborough UnitedPeterborough | 46 | 25 | 9 | 12 | 89 | 61 | 28 | 84 |
| 5 | Oxford UnitedOxford Utd | 46 | 22 | 11 | 13 | 79 | 56 | 23 | 77 |
| 6 | Barnsley | 46 | 21 | 13 | 12 | 82 | 64 | 18 | 76 |
| 7 | Lincoln CityLincoln | 46 | 20 | 14 | 12 | 65 | 40 | 25 | 74 |
| 8 | Blackpool | 46 | 21 | 10 | 15 | 65 | 48 | 17 | 73 |
| 9 | Stevenage | 46 | 19 | 14 | 13 | 57 | 46 | 11 | 71 |
| 10 | Wycombe WanderersWycombe | 46 | 17 | 14 | 15 | 60 | 55 | 5 | 65 |
| 11 | Leyton Orient | 46 | 18 | 11 | 17 | 53 | 55 | -2 | 65 |
| 12 | Wigan AthleticWigan | 46 | 20 | 10 | 16 | 63 | 56 | 7 | 62 |
| 13 | Exeter CityExeter | 46 | 17 | 10 | 19 | 46 | 61 | -15 | 61 |
| 14 | Northampton TownNorthampton | 46 | 17 | 9 | 20 | 57 | 66 | -9 | 60 |
| 15 | Bristol Rovers | 46 | 16 | 9 | 21 | 52 | 68 | -16 | 57 |
| 16 | Charlton AthleticCharlton | 46 | 11 | 20 | 15 | 64 | 65 | -1 | 53 |
| 17 | Reading | 46 | 16 | 11 | 19 | 68 | 70 | -2 | 53 |
| 18 | Cambridge UnitedCambridge | 46 | 12 | 12 | 22 | 39 | 61 | -22 | 48 |
| 19 | Shrewsbury TownShrewsbury | 46 | 13 | 9 | 24 | 35 | 67 | -32 | 48 |
| 20 | Burton Albion | 46 | 12 | 10 | 24 | 39 | 67 | -28 | 46 |
| R | Cheltenham TownCheltenham | 46 | 12 | 8 | 26 | 41 | 65 | -24 | 44 |
| R | Fleetwood TownFleetwood | 46 | 10 | 13 | 23 | 49 | 72 | -23 | 43 |
| R | Port Vale | 46 | 10 | 11 | 25 | 41 | 74 | -33 | 41 |
| R | Carlisle UnitedCarlisle | 46 | 7 | 9 | 30 | 41 | 81 | -40 | 30 |
| > League One Full Table | |||||||||
