The one-capped England international's previous deal had been due to expire at the end of the 2016-17 season.
However, the 23-year-old has now committed himself to the Liberty Stadium until the summer of 2019.
Shelvey, who joined the Swans from Liverpool for £5m in 2013, scored three goals during his 35 appearances last term.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Sheffield UnitedSheff Utd | 20 | 13 | 5 | 2 | 28 | 11 | 17 | 42 |
| 2 | Leeds UnitedLeeds | 20 | 12 | 5 | 3 | 36 | 14 | 22 | 41 |
| 3 | Burnley | 20 | 10 | 8 | 2 | 24 | 7 | 17 | 38 |
| 4 | Sunderland | 20 | 10 | 7 | 3 | 29 | 15 | 14 | 37 |
| 5 | Blackburn RoversBlackburn | 19 | 10 | 4 | 5 | 23 | 17 | 6 | 34 |
| 6 | West Bromwich AlbionWest Brom | 20 | 7 | 11 | 2 | 23 | 14 | 9 | 32 |
| 7 | Middlesbrough | 20 | 9 | 4 | 7 | 34 | 25 | 9 | 31 |
| 8 | Watford | 19 | 9 | 4 | 6 | 27 | 25 | 2 | 31 |
| 9 | Swansea CitySwansea | 20 | 7 | 6 | 7 | 21 | 19 | 2 | 27 |
| 10 | Norwich CityNorwich | 20 | 6 | 8 | 6 | 35 | 30 | 5 | 26 |
| 11 | Bristol City | 20 | 6 | 8 | 6 | 25 | 25 | 0 | 26 |
| 12 | Sheffield WednesdaySheff Weds | 20 | 7 | 5 | 8 | 23 | 29 | -6 | 26 |
| 13 | Millwall | 19 | 6 | 7 | 6 | 20 | 17 | 3 | 25 |
| 14 | Derby CountyDerby | 21 | 6 | 6 | 9 | 26 | 26 | 0 | 24 |
| 15 | Preston North EndPreston | 20 | 4 | 10 | 6 | 20 | 26 | -6 | 22 |
| 16 | Luton TownLuton | 20 | 6 | 4 | 10 | 23 | 35 | -12 | 22 |
| 17 | Coventry CityCoventry | 20 | 5 | 6 | 9 | 25 | 29 | -4 | 21 |
| 18 | Stoke CityStoke | 20 | 5 | 6 | 9 | 21 | 26 | -5 | 21 |
| 19 | Queens Park RangersQPR | 20 | 4 | 9 | 7 | 20 | 26 | -6 | 21 |
| 20 | Oxford UnitedOxford Utd | 19 | 4 | 6 | 9 | 20 | 30 | -10 | 18 |
| 21 | Portsmouth | 19 | 3 | 8 | 8 | 21 | 34 | -13 | 17 |
| 22 | Cardiff CityCardiff | 19 | 4 | 5 | 10 | 17 | 30 | -13 | 17 |
| 23 | Plymouth ArgylePlymouth | 19 | 4 | 5 | 10 | 19 | 40 | -21 | 17 |
| 24 | Hull City | 20 | 3 | 7 | 10 | 18 | 28 | -10 | 16 |
| > Championship Full Table | |||||||||
