The 28-year-old, a £1m signing from Norwich City in August 2014, has played 72 matches for the Bluebirds, scoring 13 goals.
Cardiff announced the news shortly before Tuesday night's league encounter against Derby County, which ended in a 2-0 defeat for the Welsh club.
Pilkington was not involved in the clash at the Cardiff City Stadium, having suffered a thigh injury earlier in September.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Ipswich TownIpswich | 43 | 26 | 11 | 6 | 85 | 53 | 32 | 89 |
| 2 | Leicester CityLeicester | 42 | 28 | 4 | 10 | 79 | 38 | 41 | 88 |
| 3 | Leeds UnitedLeeds | 43 | 26 | 9 | 8 | 76 | 34 | 42 | 87 |
| 4 | Southampton | 42 | 25 | 9 | 8 | 84 | 54 | 30 | 84 |
| 5 | West Bromwich AlbionWest Brom | 43 | 20 | 12 | 11 | 66 | 42 | 24 | 72 |
| 6 | Norwich CityNorwich | 43 | 21 | 8 | 14 | 76 | 60 | 16 | 71 |
| 7 | Hull City | 42 | 18 | 11 | 13 | 62 | 54 | 8 | 65 |
| 8 | Coventry CityCoventry | 42 | 17 | 12 | 13 | 66 | 52 | 14 | 63 |
| 9 | Middlesbrough | 43 | 18 | 9 | 16 | 61 | 56 | 5 | 63 |
| 10 | Preston North EndPreston | 43 | 18 | 9 | 16 | 56 | 60 | -4 | 63 |
| 11 | Cardiff CityCardiff | 43 | 18 | 5 | 20 | 48 | 60 | -12 | 59 |
| 12 | Bristol City | 43 | 16 | 10 | 17 | 50 | 46 | 4 | 58 |
| 13 | Sunderland | 43 | 16 | 8 | 19 | 52 | 50 | 2 | 56 |
| 14 | Swansea CitySwansea | 43 | 14 | 11 | 18 | 53 | 62 | -9 | 53 |
| 15 | Watford | 43 | 12 | 16 | 15 | 59 | 58 | 1 | 52 |
| 16 | Millwall | 43 | 13 | 11 | 19 | 42 | 55 | -13 | 50 |
| 17 | Blackburn RoversBlackburn | 43 | 13 | 10 | 20 | 57 | 71 | -14 | 49 |
| 18 | Plymouth ArgylePlymouth | 43 | 12 | 12 | 19 | 58 | 66 | -8 | 48 |
| 19 | Queens Park RangersQPR | 43 | 12 | 11 | 20 | 40 | 57 | -17 | 47 |
| 20 | Stoke CityStoke | 43 | 12 | 11 | 20 | 41 | 60 | -19 | 47 |
| 21 | Birmingham CityBirmingham | 43 | 12 | 9 | 22 | 48 | 64 | -16 | 45 |
| 22 | Huddersfield TownHuddersfield | 43 | 9 | 17 | 17 | 47 | 70 | -23 | 44 |
| 23 | Sheffield WednesdaySheff Weds | 43 | 12 | 8 | 23 | 36 | 67 | -31 | 44 |
| R | Rotherham UnitedRotherham | 43 | 4 | 11 | 28 | 32 | 85 | -53 | 23 |
| > Championship Full Table | |||||||||
