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 | Sunderland | 8 | 6 | 0 | 2 | 16 | 6 | 10 | 18 |
| 2 | Burnley | 8 | 5 | 2 | 1 | 14 | 4 | 10 | 17 |
| 3 | Sheffield UnitedSheff Utd | 8 | 5 | 3 | 0 | 10 | 3 | 7 | 16 |
| 4 | West Bromwich AlbionWest Brom | 8 | 5 | 1 | 2 | 12 | 6 | 6 | 16 |
| 5 | Leeds UnitedLeeds | 8 | 4 | 3 | 1 | 13 | 5 | 8 | 15 |
| 6 | Blackburn RoversBlackburn | 8 | 4 | 3 | 1 | 14 | 9 | 5 | 15 |
| 7 | Middlesbrough | 8 | 4 | 2 | 2 | 9 | 5 | 4 | 14 |
| 8 | Watford | 8 | 4 | 1 | 3 | 12 | 13 | -1 | 13 |
| 9 | Hull City | 8 | 3 | 3 | 2 | 12 | 9 | 3 | 12 |
| 10 | Norwich CityNorwich | 8 | 3 | 3 | 2 | 12 | 10 | 2 | 12 |
| 11 | Oxford UnitedOxford Utd | 8 | 3 | 2 | 3 | 12 | 10 | 2 | 11 |
| 12 | Swansea CitySwansea | 8 | 3 | 2 | 3 | 8 | 6 | 2 | 11 |
| 13 | Bristol City | 8 | 2 | 4 | 2 | 9 | 13 | -4 | 10 |
| 14 | Stoke CityStoke | 8 | 3 | 0 | 5 | 10 | 12 | -2 | 9 |
| 15 | Derby CountyDerby | 8 | 3 | 0 | 5 | 10 | 12 | -2 | 9 |
| 16 | Millwall | 8 | 2 | 2 | 4 | 12 | 11 | 1 | 8 |
| 17 | Coventry CityCoventry | 8 | 2 | 2 | 4 | 9 | 11 | -2 | 8 |
| 18 | Plymouth ArgylePlymouth | 8 | 2 | 2 | 4 | 8 | 12 | -4 | 8 |
| 19 | Sheffield WednesdaySheff Weds | 8 | 2 | 2 | 4 | 9 | 14 | -5 | 8 |
| 20 | Luton TownLuton | 8 | 2 | 2 | 4 | 8 | 13 | -5 | 8 |
| 21 | Preston North EndPreston | 8 | 2 | 2 | 4 | 7 | 12 | -5 | 8 |
| 22 | Queens Park RangersQPR | 8 | 1 | 4 | 3 | 9 | 14 | -5 | 7 |
| 23 | Portsmouth | 8 | 0 | 4 | 4 | 8 | 19 | -11 | 4 |
| 24 | Cardiff CityCardiff | 8 | 1 | 1 | 6 | 3 | 17 | -14 | 4 |
| > Championship Full Table | |||||||||
