Police are to visit knife criminals to warn them they face jail if they are caught with a blade again under new rules.
Officers will hand letters explaining the impact of the "two strikes" sentencing regime to those previously arrested for carrying a knife.
Under the new system, which came into force last week, adults convicted of possessing a knife more than once will be locked up for at least six months. The maximum term is four years.
Young offenders will face a minimum four-month detention and training order.
Scotland Yard said it is stepping up its activity to tackle knife crime to coincide with the introduction of the new guidelines.
The force said: "Officers will be visiting the homes of individuals who have previously been arrested for possession of a knife.
"They will be reminded that we know who they are and given a letter warning them that they could face a prison sentence if they carry a knife."
Police will also carry out weapons sweeps in areas where intelligence suggests offenders are hiding knives and work with Trading Standards officials to identify stores selling blades to anyone under the age of 18.
The Met is also focusing on the online sale of knives and working with the Border Force to target large consignments.
Detective Chief Superintendent Dean Haydon, the head of Trident Gang Crime Command, said: "Tackling knife crime is a key priority for the Met.
"The people of London can expect to see lots of co-ordinated and intelligence-led police activity over the coming week. We will be carrying out a variety of operations including weapon sweeps and stop and search; as well as targeting known offenders."
Yvonne Lawson, whose 17-year-old son Godwin was stabbed to death in 2010, appealed to those thinking of carrying a knife.
She said: "What I would say to anyone who carries a knife, or is thinking about carrying a knife, is what if it was your brother, your sister, your cousin or uncle that was laying there in a coffin? How would you feel then? Think about the consequences and don't pick up that knife.
"I still miss Godwin every day. The pain is enormous. It is particularly raw every Christmas and birthday that passes, knowing my wonderful, talented son is not here to share these moments with us and I will never be able to see him grow up. I would give anything to have him back with us."
Last week official figures revealed that in the year to March, crimes involving a knife or sharp instrument increased for the first time in four years.