Sociedad sit 18th in La Liga - ahead of bottom club Elche's meeting with Espanyol on Sunday - and suffered a sixth defeat in 10 games on Saturday as they went down 1-0 to Malaga in San Sebastian.
Remarkably, Sociedad's only victory so far this season came when Real Madrid suffered a 4-2 loss at the hands of Arrasate's men on August 31.
As speculation over his future intensified at the beginning of October, the coach was given a vote of confidence by club president Jokin Aperribay.
"It is not an issue of not trusting the coach. We have absolute confidence," Aperribay had told Mundo Deportivo.
However, Arrasate has now been shown the door, together with coaches Txema Lumberas and Bittor Alkiza.
"Real Sociedad have relieved Jagoba Arrasate of his first-team managerial duties," read a club statement from Sociedad, which also confirmed that Asier Santana and Imanol Alguacil will lead training as a replacement is sought.
Former Manchester United manager David Moyes has been touted as an early contender to succeed Arrasate, while Pepe Mel - who left West Brom at the end of last season - has also been linked with the role.
