Ten Hag's two-and-a-half-year spell at Old Trafford has ended after a poor start to the campaign, with United sitting 14th in the Premier League.
The 54-year-old former Ajax boss had been backed by new co-owners INEOS in the summer with a contract extension until June 2026.
That came despite the group initially speaking to a number of other candidates to replace him on the back of an eighth-placed finish in the Premier League, their worst top-flight position since 1990.
The club sanctioned around £200m of spending in the summer transfer window, but Man Utd's underwhelming start to the new campaign has now seen the manager pay the price for their patchy form.
Man Utd's new owners INEOS had backed Erik ten Hag in the summer with a contract extension until June 2026 but he leaves with the club lying 14th in the Premier League; United came eighth last season - their worst top-flight position since 1990 - but won the FA Cup