The 30-year-old Frenchman has penned a four-year deal at the Camp Nou with the option to extend it by a further 12 months.
The Catalan club has also announced that the full-back has a buyout clause of £39.5m.
Mathieu, who joined Valencia from Toulouse in 2009, scored four goals in 42 appearances last season.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Barcelona | 17 | 12 | 2 | 3 | 50 | 19 | 31 | 38 |
| 2 | Real Madrid | 16 | 11 | 3 | 2 | 34 | 13 | 21 | 36 |
| 3 | Atletico MadridAtletico | 16 | 10 | 5 | 1 | 30 | 11 | 19 | 35 |
| 4 | Athletic Bilbao | 17 | 9 | 5 | 3 | 26 | 15 | 11 | 32 |
| 5 | Villarreal | 15 | 7 | 5 | 3 | 27 | 25 | 2 | 26 |
| 6 | Real Sociedad | 16 | 7 | 3 | 6 | 16 | 11 | 5 | 24 |
| 7 | Osasuna | 16 | 6 | 6 | 4 | 22 | 25 | -3 | 24 |
| 8 | Mallorca | 17 | 7 | 3 | 7 | 16 | 20 | -4 | 24 |
| 9 | GironaGirona | 16 | 6 | 4 | 6 | 22 | 23 | -1 | 22 |
| 10 | Celta Vigo | 16 | 6 | 3 | 7 | 25 | 27 | -2 | 21 |
| 11 | Real BetisBetis | 16 | 5 | 6 | 5 | 18 | 20 | -2 | 21 |
| 12 | Rayo Vallecano | 15 | 5 | 4 | 6 | 15 | 16 | -1 | 19 |
| 13 | Sevilla | 16 | 5 | 4 | 7 | 17 | 23 | -6 | 19 |
| 14 | Las PalmasLas Palmas | 16 | 5 | 3 | 8 | 22 | 27 | -5 | 18 |
| 15 | Getafe | 16 | 3 | 7 | 6 | 11 | 13 | -2 | 16 |
| 16 | AlavesAlaves | 16 | 4 | 3 | 9 | 18 | 27 | -9 | 15 |
| 17 | Leganes | 16 | 3 | 6 | 7 | 14 | 23 | -9 | 15 |
| 18 | Espanyol | 15 | 4 | 1 | 10 | 15 | 28 | -13 | 13 |
| 19 | Valencia | 14 | 2 | 4 | 8 | 13 | 22 | -9 | 10 |
| 20 | Real ValladolidValladolid | 16 | 2 | 3 | 11 | 11 | 34 | -23 | 9 |
| > La Liga Full Table | |||||||||
