Nathaniel Armstrong, 29, was killed in the early hours of Saturday morning on the same street where Jill Dando was shot dead in 1999.
Nathaniel's cousin, Good Morning Britain weatherman Alex Beresford, posted a tribute today, writing on Twitter: "Nobody wins! Everybody loses!"
Just days ago Mr Beresford delivered a powerful speech on air about the state of knife crime in the UK.
Nobody wins! Everybody loses!💔— Alex Beresford (@alexberesfordTV)March 17, 2019
He spoke out on March 5 on the ITV breakfast show during a panel debate on whether there should be more jails in the UK.
He said: "Prison doesn't work though. It does not work.
"Ive grown up in some of these communities you guys are talking about. Some of these boys don't fear prison.
"If we don’t change the environment we won’t change anything. This has been happening for years, years, and it’s not always in the media.
"Yes, policing is one thing, but if you don’t change these boys’ environment,' he said.
"All of you guys have benefited from the environment you’ve grown up in, this work environment, I’ve benefited from it too.
"But if you don’t show these boys a different environment you won’t change anything."
Mr Beresford's agent confirmed they were cousins as friends remembered Mr Armstrong as a "big friendly giant" who loved basketball.
One of Mr Armstrong's friends, who gave his name as George, 30, said: "We don't know how this happened.
"He's got a lot of friends who live local to here. He was well-known in the local area.
"Everyone in the area would have know him from basketball."
He added: "He was super friendly, a BFG. He looked super scary - six foot seven, big beard - but super friendly. It would shock you how friendly he was."
Dozens of people paid tribute to the victim and offered support to Mr Beresford online.
One person wrote: "Nathan was a gentle giant who came through the youth centres of West London. An athlete, a scholar, a professional. Incredibly sorry for your family’s loss."
Another said: "So sorry to hear the news of your cousin."
Another person posted online: "I'm so sorry about your cousin Alex I could see how passionate you were about knife crime and how frustrated you were. My thoughts are with you and your family at this sad time."
A murder investigation is underway and police are urging witnesses to come forward.
DCI Glen Lloyd said: "This murder investigation continues apace. Police work at the crime scene is ongoing. Active enquiries are in hand.
"We are appealing for information from those who were out and about in the area at the time of the attack and saw anything of note. My team is particularly keen to trace a light skinned black male, approximately 6ft tall who was seen near the scene at the time of the incident. Did you see him? Do you know who he is? Anyone with information on his identity or whereabouts is urged to contact police."
No arrests have been made.
Witnesses are being urged to contact police on 0208 358 0100 or Crimestoppers anonymously on 0800 555 111.