The Mayor was joined by the charity’s founder Michael Smith as he emptied the bin outside the Cardinal Place Shopping Centre situated off Victoria Street.
Mr Johnson said ending ending gun and knife crime in London “remains my greatest concern and challenge.”
“Three young lives tragically lost in London this year, is three lives too many. We all have a part to play in this battle and by working closely together the police, community and schools can help rid our streets of knives.”
Mr Smith said his group wanted to “provide a safe outlet for young people to get rid of dangerous weapons quickly and easily” and said although they sometimes face initial objections from local authorities and residents, “once they see the weapons we’re taking off the streets they fully support our work.”
Praising the charity’s work Mr Johnson added: “The Words 4 Weapons charity is a fantastic example of a community effort making a real difference.”
The visit comes a day after the Mayor welcomed news that London would receive a share of £18 million of new government funding to tackle knife, gun and gang crime.
The Mayor said “every penny” of the capital’s share of the funds would be “channelled into our work to rid the streets of weapons and help prevent serious youth violence in London”
Highlighting how targeted measures can reduce knife crime, City Hall says the Met’s Operation Blunt 2 initiative has taken over 10,000 knives off London’s streets.
In a statement issued on Wednesday the Mayor said: “There is no place for knife and gun crime and I reiterate my warning to anyone involved that you will be caught and the punishments will be severe.
“Winning the war on knife crime will take targeted policing operations alongside long term preventative work in the community and this additional government funding will certainly help us with the challenge of achieving this.”
