The 26-year-old has signed a three-year contract at Hillsborough after the Owls and Hornets agreed upon an undisclosed fee.
The midfielder rejoins Wednesday after scoring three goals in 22 appearances while on loan with them last season.
McGugan signed for Watford from Nottingham Forest in 2013, scoring 11 goals in 44 appearances for the Hornets.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | West Bromwich AlbionWest Brom | 7 | 5 | 1 | 1 | 12 | 5 | 7 | 16 |
| 2 | Sunderland | 7 | 5 | 0 | 2 | 14 | 6 | 8 | 15 |
| 3 | Blackburn RoversBlackburn | 7 | 4 | 3 | 0 | 14 | 6 | 8 | 15 |
| 4 | Burnley | 7 | 4 | 2 | 1 | 13 | 4 | 9 | 14 |
| 5 | Leeds UnitedLeeds | 7 | 4 | 2 | 1 | 12 | 4 | 8 | 14 |
| 6 | Sheffield UnitedSheff Utd | 7 | 4 | 3 | 0 | 9 | 3 | 6 | 13 |
| 7 | Watford | 7 | 4 | 1 | 2 | 12 | 10 | 2 | 13 |
| 8 | Middlesbrough | 7 | 3 | 2 | 2 | 8 | 5 | 3 | 11 |
| 9 | Swansea CitySwansea | 7 | 3 | 2 | 2 | 8 | 5 | 3 | 11 |
| 10 | Norwich CityNorwich | 7 | 3 | 2 | 2 | 11 | 9 | 2 | 11 |
| 11 | Oxford UnitedOxford Utd | 7 | 3 | 1 | 3 | 10 | 8 | 2 | 10 |
| 12 | Hull City | 7 | 2 | 3 | 2 | 9 | 8 | 1 | 9 |
| 13 | Derby CountyDerby | 7 | 3 | 0 | 4 | 10 | 10 | 0 | 9 |
| 14 | Bristol City | 7 | 2 | 3 | 2 | 9 | 13 | -4 | 9 |
| 15 | Millwall | 7 | 2 | 2 | 3 | 12 | 10 | 2 | 8 |
| 16 | Plymouth ArgylePlymouth | 7 | 2 | 2 | 3 | 8 | 11 | -3 | 8 |
| 17 | Queens Park RangersQPR | 7 | 1 | 4 | 2 | 8 | 11 | -3 | 7 |
| 18 | Sheffield WednesdaySheff Weds | 7 | 2 | 1 | 4 | 9 | 14 | -5 | 7 |
| 19 | Luton TownLuton | 7 | 2 | 1 | 4 | 6 | 11 | -5 | 7 |
| 20 | Stoke CityStoke | 7 | 2 | 0 | 5 | 4 | 11 | -7 | 6 |
| 21 | Coventry CityCoventry | 7 | 1 | 2 | 4 | 6 | 11 | -5 | 5 |
| 22 | Preston North EndPreston | 7 | 1 | 2 | 4 | 4 | 12 | -8 | 5 |
| 23 | Portsmouth | 7 | 0 | 4 | 3 | 7 | 13 | -6 | 4 |
| 24 | Cardiff CityCardiff | 7 | 0 | 1 | 6 | 2 | 17 | -15 | 1 |
| > Championship Full Table | |||||||||
