Pepe Mel's team claimed their first win in three games and now find themselves level on points with fourth-placed Malaga, but with a worse goal difference than their local rivals
The Andalusians were pegged back for large parts of the game, but ultimately managed to claim the three points though a late winner by Jorge Molina.
The hosts had the majority of possession in the opening period, but despite this advantage struggled to create chances in front of Adrian's goal.
Celta spurned a wonderful chance at the end of the first half through Iago Aspas, who fired wide from inside the box after being set up by Michael Krohn-Dehli in the 40th minute.
Betis improved their game after the break and started pushing at the hosts' defence, creating a host of chances. Ruben Castro, Salva Sevilla and Molina all failed to find the target for the visitors, but the Andalusians' persistence would soon bear fruit.
With less than 10 minutes to go, Betis were rewarded for their efforts. A cross by Nacho on the left rolled into the feet of Molina, who fired past Javi Varas to give the visitors the lead.
That turn of events spurred on Celta, who threw everything they have in the remaining time until the final whistle, but ultimately had to rue missing three outstanding chances through Augusto Fernandez, Gustavo Cabral and Mario Bermejo in the closing stages of the match.
Following tonight's game, Betis find themselves in fifth place, tied on 28 points with Malaga in fourth, while Celta are 15th with 15 marks. The Andalusians' next league game sees them host Mallorca on Saturday, while the Galicians visit Atletico Madrid the day before.