Bereaved parents and anti-knife crime campaigners have called on the government to declare an emergency on violent crime.
OperationShutdown saw supporters march in London asking the next prime minister to call a meeting of the government’s Cobra emergency committee to deal with the issue.
Some demonstrators had their hands covered in fake blood.
The Home Office has been approached for comment.
The protest started in Trafalgar Square and ended at Parliament where some demonstrators doused the gates in fake blood as others chanted: “Whose streets? Our streets. Whose children? Our children.”
There was also a short skit depicting Conservative leadership candidates Jeremy Hunt and Boris Johnson as Brexit-obsessed, and dismissive of other issues.
Violent crime recorded by police in England and Wales rose by 19% in a year, in 2018, according to Home Office figures.
The number of homicides – including murder and manslaughter – rose from 649 to 739, an increase of 14%, in the 12 months to the end of September 2018.
It was the the highest total for such crimes since 2007.
Grace Aloba, 42, from Hackney, east London, whose 18-year-old son was murdered in 2015, said: “There’s not enough help for the victims afterwards. I’ve faced many sleepless nights, and I’m still dealing with depression on a daily basis; it’s not easy.
“Hopefully, the politicians will pull their socks up and help us. It’s an epidemic now.
“It’s not just in London, but country-wide.”
Ms Aloba’s son Isaiah Ekpaloba was an aspiring rapper who was killed after a botched robbery when the target fought back.
Jen Lock, from Ealing, west London, who started the campaign Lives Instead Of Knives 18 months, said: “I want to see politicians accept the problem and deal with it.
“There needs to be more action. We need more police – it’s a national epidemic.”