The 27-year-old victim was found by police suffering a single stab wound in Balham High Road at 11.30pm on Tuesday.
Officers gave the man first aid and he was taken to hospital where his injuries were described as not life-threatening.
So far no arrests have been made in connection with the attack which police described as a suspected robbery.
A spokesperson for the Met Police said: “Officers attended and found a man suffering from a stab injury. They immediately provided first aid.
“The 27-year-old man was taken by the London Ambulance Service to a south London hospital; his injuries are not believed to be life-threatening.
“A crime scene remains in place and the road is partially closed to traffic.”
Anyone with information is asked to call police via 101 quoting reference Cad 8134/24Aug.
