Police were called to Primrose Hill shortly before the midnight countdown on Sunday (December 31) at 11.40pm, to a boy being stabbed.
Despite the efforts of emergency services, the boy, believed to be 16, was pronounced dead.
His family have been informed and will be supported by specialist officers, the Metropolitan Police have said.
A male, whose age is not disclosed at this time, has been arrested on suspicion of murder. He was taken into police custody.
Extensive police cordons remain in place as officers conduct forensic examinations of the scene and the surrounding area.
The Metropolitan Police says that officers believe the area was “busy with people” at the time.
Footage shared online shows crowds of people gathered at the top of the hill viewpoint in anticipation to watch the fireworks, despite there being no official displays taking place in the area.
Days before the big night, Camden Police stated the hill will close at 1am.