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 | 5 | 5 | 0 | 0 | 17 | 4 | 13 | 15 |
| 2 | Atletico MadridAtletico | 5 | 3 | 2 | 0 | 9 | 2 | 7 | 11 |
| 3 | Real Madrid | 5 | 3 | 2 | 0 | 9 | 2 | 7 | 11 |
| 4 | Villarreal | 5 | 3 | 2 | 0 | 11 | 8 | 3 | 11 |
| 5 | AlavesAlaves | 6 | 3 | 1 | 2 | 9 | 7 | 2 | 10 |
| 6 | Athletic Bilbao | 6 | 3 | 1 | 2 | 8 | 6 | 2 | 10 |
| 7 | Celta Vigo | 5 | 3 | 0 | 2 | 13 | 10 | 3 | 9 |
| 8 | Real BetisBetis | 5 | 2 | 2 | 1 | 5 | 4 | 1 | 8 |
| 9 | Mallorca | 6 | 2 | 2 | 2 | 4 | 4 | 0 | 8 |
| 10 | Rayo Vallecano | 5 | 2 | 1 | 2 | 7 | 6 | 1 | 7 |
| 11 | GironaGirona | 5 | 2 | 1 | 2 | 8 | 8 | 0 | 7 |
| 12 | Espanyol | 5 | 2 | 1 | 2 | 5 | 5 | 0 | 7 |
| 13 | Osasuna | 5 | 2 | 1 | 2 | 6 | 10 | -4 | 7 |
| 14 | Sevilla | 6 | 1 | 2 | 3 | 5 | 8 | -3 | 5 |
| 15 | Leganes | 6 | 1 | 2 | 3 | 3 | 7 | -4 | 5 |
| 16 | Real Sociedad | 6 | 1 | 1 | 4 | 3 | 7 | -4 | 4 |
| 17 | Real ValladolidValladolid | 5 | 1 | 1 | 3 | 2 | 13 | -11 | 4 |
| 18 | Getafe | 5 | 0 | 3 | 2 | 2 | 4 | -2 | 3 |
| 19 | Las PalmasLas Palmas | 5 | 0 | 2 | 3 | 6 | 10 | -4 | 2 |
| 20 | Valencia | 5 | 0 | 1 | 4 | 3 | 10 | -7 | 1 |
| > La Liga Full Table | |||||||||
