Police said the victim was also “slashed with a knife” and they had arrested a suspect in Ealing at 10pm on Thursday.
The condition of the victim has not been disclosed but an arrest has been made.
MPS Specials, a volunteer wing of Scotland Yard, tweeted a video of their response car hurtling towards the scene.
A police emergency call operator tells the unit “Three people fighting with knives, that’s all we have at the moment”, over a crackling radio.
The force added: “MSC Officers from West Area deployed to @ealingMPS overnight, attending an emergency call where a male had been stabbed with a pitchfork and slashed with a knife.
“The suspect was arrested at the scene.”
They later posted an image of two knives taken from the scene.
Scotland Yard has been approached for further comment.