Chief executive Ed Woodward arrived at Carrington at 8am on Tuesday morning to inform the Scot face-to-face of the news.
Moyes had already been informed of his fate and thanked club staff at the training complex in anticipation of his departure. The players were not present at the time.
A tweet on the club’s official Twitter account read: ‘BREAKING: Manchester United announces that David Moyes has left the club. The club would like to place on record its thanks for the hard work, honesty and integrity he brought to the role.’
It emerged on Monday that United’s owners, the Glazer family, had lost patience with Moyes after a dismal season that has seen the reigning Barclays Premier League champions’ slump to seventh in the table.
United are confident of landing Holland coach Louis van Gaal as his replacement once they have tied up details of the manager’s severance package.
The Barclays Premier League champions have already made contact with the Dutchman and he wants to join United after the World Cup.
Moyes has been sacked having not even completed one year of a six-year contract and will receive a hefty compensation package.
The Scot, on a day off on Monday, is understood to have been hurt and angry after learning of his fate on newspaper websites.
Ryan Giggs will take temporary charge for Saturday’s home match with Norwich City.
Despite the expensive signings of Marouane Fellaini last summer and Juan Mata in January, United have failed to keep pace with their rivals and mount any kind of title challenge.
Moyes, who moved from Everton last summer to replace Sir Alex Ferguson, has also overseen failure in the cup competitions.
United were eliminated by Swansea City in the third round of the FA Cup, by Sunderland in the semi-finals of the Capital One Cup and by Bayern Munich in the quarter-finals of the Champions League.
Taking all competitions into account, United have won 27 of 51 matches during the Moyes tenure, drawing nine and losing 15.