The former Everton and Manchester United boss moved to San Sebastian, Spain, looking to revive his coaching career in La Liga after being sacked by the Red Devils just seven months into his contract at Old Trafford.
Moyes, 52, was shown the door one year after taking charge of La Real.
A statement from the Basque outfit read: “Real Sociedad has decided to rescind the contract of the coach of the first team David Moyes.”
His assistant Billy McKinlay has also parted company with the club.
In the statement, Real Sociedad said: “The club wishes to thank David Moyes as well as Billy McKinlay for the contribution, professionalism and dedication that they have shown during the time in charge of the first team.
“We wish them the best of luck in their professional and personal futures.”
Friday’s 2-0 away defeat to Las Palmas was La Real’s fourth loss in their last five league games and left them in 16th place with nine points from their opening 11 league games - the same position the club was in when Moyes took over.
Under Moyes, Real Sociedad have won just twice this season.
Moyes, whose contract was set to expire in June 2016, won 12 games out of 38 to guide La Real to a 12th-place finish in the 2014-15 campaign.
Former Barcelona assistant coach Eusebio Sacristan is the favourite to replace Moyes.
The Spanish tactician has been out of a job since being dismissed by Barca’s reserves in February 2015.
Eusebio, 51, coached Celta Vigo in the Segunda Division in the 2009-10 campaign but has yet to guide a Primera Division side.
Real Sociedad host Sevilla in Anoeta after the international break before travelling to the Nou Camp to face defending Spanish champions Barcelona on November 28.