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 | Leeds UnitedLeeds | 26 | 15 | 8 | 3 | 48 | 19 | 29 | 53 |
| 2 | Burnley | 26 | 14 | 10 | 2 | 31 | 9 | 22 | 52 |
| 3 | Sheffield UnitedSheff Utd | 26 | 16 | 6 | 4 | 36 | 17 | 19 | 52 |
| 4 | Sunderland | 26 | 14 | 8 | 4 | 39 | 22 | 17 | 50 |
| 5 | Middlesbrough | 26 | 11 | 8 | 7 | 43 | 32 | 11 | 41 |
| 6 | West Bromwich AlbionWest Brom | 26 | 9 | 13 | 4 | 32 | 21 | 11 | 40 |
| 7 | Blackburn RoversBlackburn | 25 | 11 | 6 | 8 | 28 | 23 | 5 | 39 |
| 8 | Bristol City | 26 | 9 | 10 | 7 | 33 | 30 | 3 | 37 |
| 9 | Watford | 25 | 11 | 4 | 10 | 35 | 36 | -1 | 37 |
| 10 | Sheffield WednesdaySheff Weds | 26 | 10 | 7 | 9 | 38 | 40 | -2 | 37 |
| 11 | Norwich CityNorwich | 26 | 9 | 9 | 8 | 43 | 37 | 6 | 36 |
| 12 | Swansea CitySwansea | 26 | 9 | 7 | 10 | 30 | 30 | 0 | 34 |
| 13 | Queens Park RangersQPR | 26 | 7 | 11 | 8 | 29 | 34 | -5 | 32 |
| 14 | Millwall | 25 | 7 | 9 | 9 | 24 | 23 | 1 | 30 |
| 15 | Preston North EndPreston | 26 | 6 | 12 | 8 | 28 | 34 | -6 | 30 |
| 16 | Coventry CityCoventry | 26 | 7 | 8 | 11 | 34 | 37 | -3 | 29 |
| 17 | Oxford UnitedOxford Utd | 25 | 7 | 7 | 11 | 28 | 40 | -12 | 28 |
| 18 | Derby CountyDerby | 26 | 7 | 6 | 13 | 31 | 35 | -4 | 27 |
| 19 | Stoke CityStoke | 26 | 6 | 9 | 11 | 24 | 32 | -8 | 27 |
| 20 | Luton TownLuton | 26 | 7 | 4 | 15 | 27 | 44 | -17 | 25 |
| 21 | Portsmouth | 24 | 5 | 8 | 11 | 30 | 41 | -11 | 23 |
| 22 | Hull City | 26 | 5 | 8 | 13 | 25 | 36 | -11 | 23 |
| 23 | Cardiff CityCardiff | 25 | 5 | 8 | 12 | 25 | 40 | -15 | 23 |
| 24 | Plymouth ArgylePlymouth | 25 | 4 | 8 | 13 | 24 | 53 | -29 | 20 |
| > Championship Full Table | |||||||||
