Graham Potter said he is "disappointed" to be sacked by West Ham, although he admitted that "results had not been good enough."
The Chelsea boss Potter was relieved of his duties just two days out from West Ham's match against Everton. Sources have told ESPN that Nuno Espirito Santo is to replace him.
"I am incredibly disappointed to be leaving West Ham United football club, particularly without being able to achieve what we set out to achieve at the start of our journey in East London," Potter said in a statement via the League Managers' Association (LMA).
"I do however fully acknowledge that the results have just not been good enough up to now."
Last weekend, Potter suffered his latest defeat in charge at home to Crystal Palace, and the club's owners have now acted with West Ham on the hunt for a fourth manager during the last 18 months.
West Ham turned to Potter at the start of 2025 after Julen Lopetegui -- the successor of long-serving boss David Moyes -- lasted only 22 matches.
Lopetegui was sacked after heavy defeats to Liverpool and Manchester City, but won seven of his fixtures in charge -- a slight improvement on Potter's final record.
Potter accepted West Ham's advances in January after he turned down multiple job proposals during a near two-year spell out of management following his dismissal by Chelsea.
After a chastening 31-game spell in west London, Potter travelled across the capital and whilst his West Ham debut ended in an FA Cup defeat at Aston Villa, a 3-2 home win over Fulham in his first league fixture provided the type of thrill which had been missing at London Stadium.
However, he failed to kick on at the London Stadium, and after a summer that saw the departure of Mohammed Kudus to rivals Tottenham, fans' frustration heightened.
Potter's lowest ebb came this season, with four defeats in five games leaving them in 19th in the Premier League. West Ham are also out of the Carabao Cup after a late collapse to Wolves.
"Firstly, thank you to the board for offering me the opportunity to manage the team during the past eight months," Potter added.
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"It was an honour and a privilege to manage such a historic club, which holds such strong values for footballing traditions and passion for the game.
"I'd like to thank all the staff at the club who made me feel so welcome, the playing squad and their continued efforts during my time -- and lastly the fans, who have been so supportive during what has been a difficult journey at times.
"I wish the club nothing but the best of luck for the future.
"Thank you and goodbye for now."
Information from PA contributed to this report.