The incident happened in High Road near London Road at around 12.55pm today (December 1).
Officers and London Ambulance Service crews attended and found a man who had been stabbed.
He was taken to hospital for treatment but later died.
His next of kin have been informed and are being supported by specialist officers.
No arrests have been made at this early stage.
Detective Chief Superintendent Luke Williams, who leads policing for the area said: “My thoughts are with the victim’s loved ones at this unimaginably difficult time.
“Knife crime has a devastating impact on communities and our officers are here to support local residents with any concerns.
“Residents can expect to see an increased police presence over the next few days.
“In the meantime, our dedicated officers are working at speed to piece together this tragic incident.
“Anyone with relevant information should not hesitate to share it with us.”
The investigation is being led by the Met’s homicide command.
Those with information can contact 101, quoting 3333/1DEC or anonymously via Crimestoppers on 0800 555 111.
A formal post-mortem examination will take place in due course.