The Vox party, which opposes illegal immigration and Catalan independence, won 12 seats in the Andalusia parliamentary elections.
Vox, which opposes illegal immigration and Catalan independence, won 12 seats in the Andalusia parliamentary elections, bringing an end to three decades of socialist rule in the southern Spanish region.
The party had been predicted to take five seats before the votes were counted on Sunday evening.
"The Andalusians have made history... and got rid of 36 years of socialist rule," Vox leader Santiago Abascal said.
French far-right leader Marine Le Pen sent her "warm congratulations" to Vox after the results.
The election results leave right-wing parties poised to take control of the 109-seat regional parliament.
Spain's Socialist Workers' Party suffered their worst result in history, picking up 33 seats, while its potential left-wing ally Adelante Andalusia (Forward Andalusia) won 17 seats.
Meanwhile, the conservative Popular Party won 26 seats and the Ciudadanos liberals took 21 seats.
Andalusia's election was something of a test for Spanish prime minister Pedro Sanchez as it was the first vote since he took office in June.
Next year Spain will have municipal, regional and European elections which could be an even tougher test for the ruling Socialists.
Ciudadanos' leader Juan Marin has ruled out a coalition with the Socialists and said he would present himself as a potential leader of the region.
He said: "We won't support a government of (regional Socialist leader) Susana Diaz or with the Socialist party. They've lost the confidence of the Andalusia people and so that possibility doesn't exist."
Ms Diaz said: "Despite winning the election it is a sad night for the Socialist Party.
"There has been a real loss of ground for the Left. But the worst thing is that the extreme right, a phenomenon that has appeared in the rest of Europe, has arrived here."
As well as a stance against Catalan independence, Vox wants to restrict abortion and roll back domestic violence laws.