Operation Trident has started a new campaign to stop 11 to 16-year-olds turning to gun crime.
Operation Trident investigates gun crime in the black community
The billboard campaign features a dead man in a mortuary fridge with the message: "Carrying a gun can get you into the coolest places."
More than 80 of the billboards went up in six London boroughs on Sunday night.
A spokesman said: "This forceful, cutting-edge campaign is designed to remind young people of the deadly consequences of carrying a gun."
Lee Jasper, the chairman of the Trident Independent Advisory Group, said: "Gun crime devastates communities. It creates fear, destroys lives and threatens the very core of our communities."
The new campaign will run for the next two weeks.
Assistant Commissioner Steve House, the head of the Metropolitan Police's specialist crime directorate, said: "The aim of this year's campaign is to challenge the myth that gunmen deserve respect by showing the true consequences of carrying a gun.
"Trident is concerned that people are starting to carry guns from an increasingly young age.
"That is why this campaign is principally aimed at 11 to 16-year-olds in London, especially those living in gun crime hotspots, with a view to preventing them from becoming the gunmen of the future."
The Met's Operation Trident was set up in 1998 to deal with gun crime affecting London's black community.