Police were called at approximately 5.34pm on Saturday, 6 March to reports of a fight in Edington Road, Abbey Wood.
Officers attended along with the London Ambulance Service and found an 18-year-old man with a stab wound to his chest. He was pronounced dead at the scene.
His next of kin has been informed and are being supported by specialist officers. Formal identification is yet to take place but officers are confident that he is Mazaza Owusu-Mensah.
Detectives from the Met’s Specialist Crime Command have launched a murder investigation and enquiries are well under way.
Detective Chief Inspector John Neil said: “This was a senseless attack on a young man that has left a family grieving. We are doing everything we can to identify those responsible.
“This incident took place on a residential street. We know that in the current circumstances, many people are at home. If you heard or saw anything around the time of this incident, we want to hear from you.
“If you have seen discussions on social media or have any other information about who is responsible, we would encourage you to come forward and tell us what you know.
“I understand that to do so can be daunting, but it could be the piece in the puzzle that helps us get justice for Mazaza’s family. My officers are waiting for your call.”
Anybody who can assist detectives with their investigation is urged to call 101 or tweet @MetCC providing the reference CAD5771/06MAR.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111.