Potter, 50, is the second Premier League manager to lose his job this season after taking over the troubled London Stadium club in January, when they were in 14th position.
“Results and performances over the course of the second half of last season and the start of the 2025/26 season have not matched expectations,” the club said in a statement.
“The board of directors believe that a change is necessary in order to help improve the team’s position in the Premier League as soon as possible.”
West Ham have picked up just three points from their opening five Premier League games and are due to face Everton on Monday.
Reports in the British media have tipped Portuguese coach Espirito Santo as Potter’s successor.
The 51-year-old former Wolves and Spurs boss was sacked by Forest owner Evangelos Marinakis three weeks ago due to poor personal relations.
He lifted Forest to European competition for the first time in 30 years last season, but Marinakis was upset they let slip a promising opportunity to qualify for the Champions League.
Former Chelsea and Brighton boss Potter won only six of his 25 matches since January having replaced Julen Lopetegui, who lasted only 22 matches after taking over from long-serving boss David Moyes.
A 3-0 win at Nottingham Forest last month provided some respite, but West Ham went down by the same score to Tottenham after the September international break and another London loss to Crystal Palace last weekend proved the final straw for Potter.
Potter admitted last Saturday that their latest setback, the 2-1 home defeat against Crystal Palace, was a “tough moment” as he and his team were booed off at the final whistle.
The club confirmed that assistant coach Bruno Saltor, first team coaches Billy Reid and Narcis Pelach, lead goalkeeper coach Casper Ankergren, and goalkeeper coach Linus Kandolin have also left with immediate effect.
“The process of appointing a replacement is underway. The club will be making no further comment at this time,” the club statement added. (AFP)
