Diego Castro's 31st-minute goal decided the match in Getafe's favour at the Coliseum Alfonso Perez as Betis were brought crashing back to earth after winning their opening four games since returning to the top flight.
Despite the loss though, Betis were still a point clear of reigning champions Barcelona, Levante and local rivals Sevilla at the top of the standings, while Getafe climbed up to 16th place after claiming their first victory of the campaign.
Getafe had picked up just one point from their opening four games but they started in determined mood tonight, with Pedro Leon bringing a fine save out of Inaki Goitia with an early free-kick.
The home side then took the lead just after the half-hour mark when Castor got on the end of Juan Valera's cross to turn the ball past Goitia.
Leon brought another save out of the visiting goalkeeper as Getafe sought to increase their lead before the break.
After struggling to create much in the first half, Betis started the second period with Jefferson Montero and Jorge Molina sending efforts wide, before Jonathan Pereira drew a fantastic save out of Miguel Moya in the 64th minute.
Betis striker Roque Santa Cruz also failed to hit the target with a header and although he managed to do better in the 85th minute, Moya was able to save comfortably.
Moya also parried away Benat Etxebarria's 25-yard effort with a minute to go as Betis sought a late leveller.
However, there would be no fairytale ending for the Segunda Division champions and Getafe almost added to their tally deep into stoppage time when Miku saw his close-range shot brilliantly saved by Moya.