The 27-year-old, whose transfer fee is said to be £7m, has penned a four-year deal at Vicarage Road.
A £5m signing for the Magpies from Feyenoord in July 2014, the Netherlands international made 78 appearances for the Tyneside club, scoring four goals.
Janmaat began his career at Eredivisie side Heerenveen before a move in 2012 and a two-year spell with the Rotterdam giants.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Leeds UnitedLeeds | 16 | 9 | 5 | 2 | 28 | 12 | 16 | 32 |
| 2 | Sunderland | 16 | 9 | 5 | 2 | 26 | 12 | 14 | 32 |
| 3 | Sheffield UnitedSheff Utd | 16 | 10 | 4 | 2 | 21 | 9 | 12 | 32 |
| 4 | Burnley | 16 | 8 | 6 | 2 | 19 | 6 | 13 | 30 |
| 5 | Middlesbrough | 16 | 8 | 3 | 5 | 29 | 19 | 10 | 27 |
| 6 | West Bromwich AlbionWest Brom | 16 | 6 | 8 | 2 | 18 | 11 | 7 | 26 |
| 7 | Watford | 16 | 8 | 2 | 6 | 25 | 24 | 1 | 26 |
| 8 | Millwall | 16 | 6 | 6 | 4 | 19 | 14 | 5 | 24 |
| 9 | Blackburn RoversBlackburn | 15 | 6 | 4 | 5 | 19 | 17 | 2 | 22 |
| 10 | Bristol City | 16 | 5 | 7 | 4 | 20 | 20 | 0 | 22 |
| 11 | Derby CountyDerby | 16 | 5 | 5 | 6 | 20 | 20 | 0 | 20 |
| 12 | Stoke CityStoke | 16 | 5 | 5 | 6 | 19 | 20 | -1 | 20 |
| 13 | Norwich CityNorwich | 16 | 4 | 7 | 5 | 25 | 24 | 1 | 19 |
| 14 | Swansea CitySwansea | 16 | 5 | 4 | 7 | 14 | 14 | 0 | 19 |
| 15 | Sheffield WednesdaySheff Weds | 16 | 5 | 4 | 7 | 18 | 26 | -8 | 19 |
| 16 | Luton TownLuton | 16 | 5 | 3 | 8 | 18 | 26 | -8 | 18 |
| 17 | Coventry CityCoventry | 16 | 4 | 5 | 7 | 22 | 23 | -1 | 17 |
| 18 | Oxford UnitedOxford Utd | 16 | 4 | 5 | 7 | 19 | 24 | -5 | 17 |
| 19 | Plymouth ArgylePlymouth | 16 | 4 | 5 | 7 | 17 | 28 | -11 | 17 |
| 20 | Preston North EndPreston | 16 | 3 | 7 | 6 | 16 | 24 | -8 | 16 |
| 21 | Cardiff CityCardiff | 16 | 4 | 4 | 8 | 15 | 24 | -9 | 16 |
| 22 | Hull City | 16 | 3 | 6 | 7 | 16 | 21 | -5 | 15 |
| 23 | Portsmouth | 15 | 2 | 6 | 7 | 16 | 28 | -12 | 12 |
| 24 | Queens Park RangersQPR | 16 | 1 | 8 | 7 | 13 | 26 | -13 | 11 |
| > Championship Full Table | |||||||||
