The home side took the lead on the stroke of half time when Mesut Ozil finished from close range, but Betis were unlucky to enter the break behind.
Betis started brightly in the second period, but it was two for Madrid after 57 minutes when Karim Benzema coolly found the bottom corner.
The away side had one back late on from a Jorge Molina penalty, but Ozil made sure of the points in the second-half stoppage-time.
Here, Sports Mole dissects the 90 minutes of action between the two La Liga rivals.
On target: 8
On target: 7
Was the result fair?
There is not any possible situation where anything other than a Madrid win would have reflected the match this evening. That is not to say that Betis did not have chances of their own, but they never really had an extended period of pressure until the very latter stages, when they had too much to do. A narrow home victory was indeed a fair result.
Real Madrid's performance
It was hardly a vintage performance from Madrid as coach Jose Mourinho made changes with the Champions League clash against Borussia Dortmund on the horizon, but it was a professional display from those selected. In truth, the three points were never in doubt at any point during the 90 minutes despite their defence coming under pressure late on.
Real Betis's performance
Betis are certainly a good team to watch, but their defensive deficiencies continue to cost them. The fact that they are sniffing around the top four is credit to their attacking players, but they have conceded more goals than bottom side Celta Vigo this season.
Sports Mole's man of the match
Mesut Ozil: It wasn't really a match full of star performers, but the German radiated class with every touch and added two goals. It was a surprise that he started with Dortmund to come next week, but he has gained some much-needed match fitness.
Biggest gaffe of the match
Despite being caught out on a number of occasions in the early stages, Betis continued to play a high line. Eventually it was their undoing as Ozil slipped behind before finishing in first-half stoppage-time. They may be exciting to watch, but they always give teams a chance with their defensive positioning.
Alfonso Alvarez had a comfortable 90 minutes of football this evening. The Spaniard was not called into action on too many occasions in the first period, but was quick on the scene when it was deemed necessary. Overall, neither manager would have had many complaints.
Real Madrid: Madrid travel to Borussia Dortmund on Wednesday in the first leg of their semi-final clash in the Champions League.
Real Betis: Betis will attempt to return to winning ways when they welcome a resurgent Deportivo La Coruna on April 29.