The incident between a pedestrian and a car happened in Green Lane near Rosehill just after 6.50pm yesterday (March 3).
Officers and London Ambulance Service crews attended and found a man injured.
He was pronounced dead at the scene shortly after.
No arrests have been made as police enquiries continue.
Road closures were put in place as the incident was dealt with, however, it has since reopened.
A spokesperson for Metropolitan Police said: “Police were called to a road traffic collision between a car and a pedestrian in Green Lane, Morden at 18:51hrs on Monday, 3 March.
“Despite the London Ambulance Service and officers providing treatment to a 49-year-old man, the pedestrian, he was sadly pronounced dead at the scene.
“No arrests have been made, enquiries are ongoing. The road is now reopen.”
