Emergency services were called to a fight in Sevenoaks Way in Orpington at midnight last night (August 2).
On arrival police and ambulance found a man with stab wounds.
He was treated at the scene before being taken to hospital, his condition is currently unknown.
There have been no arrests.
A spokesperson for Metropolitan Police said: “Around 00:00hrs on Saturday, 2 August, officers attended Sevenoaks Way, Orpington, alongside the London Ambulance Service and London’s Air Ambulance following reports of an altercation.
“A man was treated at the scene for stab wounds. He was taken to hospital, where we await an update on his condition.
“No arrests have been made at this early stage of the investigation.
“Anybody who witnessed the incident – or who has information – should contact the police on 101, quoting 9031/02AUG.”