Getafe players celebrate with Jaime Mata took Getafe to 42 points from 26 games, a two-point advantage over fifth-placed Alaves, while Betis are seventh on 36 points.
Getafe defender Cabrera headed the Madrid side in front against an out-of-form Betis outfit in the 20th minute following a short-corner routine.
The visitors doubled their advantage just before half time when Mata latched on to a through pass from strike partner Jorge Molina and calmly stuck the ball into the bottom corner.
Betis, who were knocked out of the Copa del Rey semifinals by Valencia on Thursday, pulled a goal back in the 75th minute with a thumping finish from captain Joaquin and then had an effort from striker Jese ruled out for offside.
The Seville team were booed off the pitch at full-time after a fourth defeat in eight games in all competitions, while some fans also chanted for coach Quique Setien to be sacked.