Police were called at around 3.30pm yesterday (Tuesday) to reports of a stabbing near Evans Grove, and an 18-year-old boy was rushed to a central London hospital where he later died.
Officers, London Ambulance Service and London's Air Ambulance attended the scene.
The man has been named as Jamil Palmer. Next of kin have been informed.
A post-mortem examination will be scheduled in due course.
An investigation has been launched by detectives from the Homicide & Major Crime Command, based at Putney, under Detective Chief Inspector Noel McHugh.
DCI Noel McHugh said: "I would like to urge anyone who was near Evans Grove, Feltham, between 1500 and 1530hrs on Tuesday, 6 May, to get in touch with police.
"They may well have seen something which could be of vital importance.
“I would also like to appeal directly to those that have knowledge of this murder to contact police."
A local resident told the Mirror: “Earlier today a teenage boy was stabbed whilst walking across Crane Park, Hanworth, Feltham.
'My daughter may have been the last to see stab victim alive'
"The air ambulance arrived, but it was too late. There are still a large number of police at the scene gathering evidence.”
An investigation has been launched by detectives from the Homicide & Major Crime Command, based at Putney, but there have been no arrests.
A 44 year old woman who lives on Watermill way off Evans grove said: "It's scary really. its really sad and a tragic loss. A handful of people spoil it for others in the area. My son went to the shop for me and when he came back he told me someone had been stabbed."
Two youths have been arrested in connection with the killing.
Anyone with information should call the incident room on 020 8785 8099 or call Crimestoppers anonymously on 0800 555 111.
