Emergency services rushed to the scene in Ilford shortly before 9.30pm on Friday.
The victim, believed to be aged in his 30s, was found suffering from a stab injury in Southdown Crescent.
Police and paramedics battled to save him but he was pronounced dead at the scene just over an hour later.
A Met Police spokesman confirmed no arrests had been made.
He added: "Officers are in the process of informing next of kin. Formal identification awaits.
"A post-mortem examination will be held in due course.
"A crime scene remains in place. Enquiries into the circumstances continue."
Anyone with information is asked to call police via 101 or tweet @MetCC quoting reference Cad 7789/09Oct.
Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111.