The Whites romped to a 3-0 lead over David Moyes' side at Craven Cottage, with Raul Jiminez, Willian and Cenk Tosun giving them a comfortable lead at half-time.
Willian has now scored his last eight Premier League goals at Craven Cottage, with only Bobby Zamora having a longer run of goals coming at home for Fulham in the competition.
Things got even better for Fulham after half-time with Harry Wilson making it 4-0.
Carlos Vinicius then made it 5-0 late on to pile on the misery for the Hammers.
Those goals have also put Fulham at the top of a special table, with the club now the highest scorers in the Premier League since the start of November, with 17.
READ MORE ON FULHAM
West Ham fans have nightmare trip to Craven Cottage as boat crashes into a bridge
AEW star has diplomatic response to CM Punk's stunning WWE return
Marco Silva's side also made it four top flight matches in a row that they've scored more than three goals - the first time that they've managed it since October 1961.
Fulham were tipped to struggle in front of goal following the decision to sell Aleksandar Mitrovic Al-Hilal over the summer.
But in truth Silva's side are quickly becoming one of the most entertaining teams to watch in the Premier League.