City Hall published a detailed analysis, using police and NHS data since 2012, of the causes and extent of knife and gun crime and its links to poverty.
There were 52 murders of people under 25 in 2018, according to the Met police. The number of victims of serious youth violence rose by 71 per cent between 2012/13 and 2017/18, but fell four per cent in the most recent financial year, the research said.
The Mayor today called for “honesty” about the scale of the problem and the level of commitment needed to bring an end to the “bloodshed” by using a public health approach.
Westminster, Haringey, Southwark, Lambeth, Islington, Tower Hamlets, Camden and Hackney had the highest victim rates, based on the number of attacks per 1,000 residents under 25.
Today’s research said incidents involving school children were most likely to occur soon after the end of the school day. Those involving young adults were most common after 10pm and at weekends.
A total of 39 per cent of victims were white, 26 per cent black and 16 per cent Asian.
White people accounted for 41 per cent of attackers, while 35 per cent were black.
Mr Khan, addressing youth and community leaders and bereaved families in a youth club in Bermondsey, said: “There’s never any excuse for criminality. Those who commit crimes must pay for their actions.
“But we have to face the reality that for some young people growing up today, violence has become normalised.”
The Mayor’s violence reduction unit today announced it would expand after-school clubs in high-crime areas. Measures to stop reoffending will also be expanded in prisons and young offender institutions.
When asked whether it would take a decade or more to achieve change, Mr Khan said the Met's violence reduction task force had carried out more than 5,000 arrests and taken more than 2,000 knives off the streets.
He added: "We are making progress but to make transformative change will take some time.
"Londoners can't afford to wait 10 years for our city to be as safe as it can be."
The Mayor, who often meets grieving families, spoke of the personal impact of the scale of the crime epidemic.
He said: "I often lie awake at night with an overwhelming sense of apprehension. How many Londoners will be the victims of violence over the coming days?
"How many women will have to suffer sexual assault or domestic violence? How many families will be left grieving due to bloodshed on our streets?"