The 32-year-old, who left Hamburger SV at the end of last season, had been widely tipped with a switch to the La Liga club.
Van der Vaart has now officially completed his move to Los Verdiblancos on what is thought to be a three-year deal.
Betis won promotion from the Spanish Segunda Division in 2014-15, finishing five-points clear of third-place Girona.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Barcelona | 13 | 11 | 0 | 2 | 40 | 12 | 28 | 33 |
| 2 | Real Madrid | 12 | 8 | 3 | 1 | 25 | 11 | 14 | 27 |
| 3 | Atletico MadridAtletico | 13 | 7 | 5 | 1 | 19 | 7 | 12 | 26 |
| 4 | Villarreal | 12 | 7 | 3 | 2 | 23 | 19 | 4 | 24 |
| 5 | Osasuna | 13 | 6 | 3 | 4 | 17 | 20 | -3 | 21 |
| 6 | Athletic Bilbao | 13 | 5 | 5 | 3 | 19 | 13 | 6 | 20 |
| 7 | Real BetisBetis | 13 | 5 | 5 | 3 | 14 | 12 | 2 | 20 |
| 8 | Real Sociedad | 13 | 5 | 3 | 5 | 11 | 10 | 1 | 18 |
| 9 | Mallorca | 13 | 5 | 3 | 5 | 10 | 10 | 0 | 18 |
| 10 | GironaGirona | 13 | 5 | 3 | 5 | 16 | 17 | -1 | 18 |
| 11 | Celta Vigo | 13 | 5 | 2 | 6 | 20 | 22 | -2 | 17 |
| 12 | Rayo Vallecano | 12 | 4 | 4 | 4 | 13 | 13 | 0 | 16 |
| 13 | Sevilla | 13 | 4 | 3 | 6 | 12 | 18 | -6 | 15 |
| 14 | Leganes | 13 | 3 | 5 | 5 | 13 | 16 | -3 | 14 |
| 15 | AlavesAlaves | 13 | 4 | 1 | 8 | 14 | 22 | -8 | 13 |
| 16 | Las PalmasLas Palmas | 13 | 3 | 3 | 7 | 16 | 22 | -6 | 12 |
| 17 | Getafe | 13 | 1 | 7 | 5 | 8 | 11 | -3 | 10 |
| 18 | Espanyol | 12 | 3 | 1 | 8 | 11 | 22 | -11 | 10 |
| 19 | Real ValladolidValladolid | 13 | 2 | 3 | 8 | 10 | 25 | -15 | 9 |
| 20 | Valencia | 11 | 1 | 4 | 6 | 8 | 17 | -9 | 7 |
| > La Liga Full Table | |||||||||
