Harry Redknapp has parted company with West Ham after almost seven years in the job, according to a report on the club's official website.
Redknapp led the Hammers to FA Cup victories at Manchester United and Sunderland this year but the team currently lie 14th in the Premiership.
The 54-year-old was involved in a British record transfer deal earlier this season when Rio Ferdinand left Upton Park for Leeds for £18million.
I've had a chat with the chairman and just feel it's been a tough season," Redknapp was quoted as saying on the website.
"The last eight weeks or so of the season haven't been particularly enjoyable and I feel that maybe it's time for a change."
Redknapp, a former player with the London club, has been manager since August 1994, having been assistant to the previous boss Billy Bonds.
He was the second-longest serving manager in the Premiershipafter Manchester United's Alex Ferguson.