Metropolitan Police Commissioner Sir Bernard Hogan-Howe joined a foot patrol of neighbourhood watch group Shomrim on Tuesday which took in a number of Stamford Hill synagogues.
Sir Bernard also handed over a letter praising Shomrim as "a well-established voluntary organisation which acts in the interests of the community and neighbourhoods within Hackney and Haringey," The letter added: "Their efforts complement the role of local officers and undoubtedly help local residents interact with the police."
The group says its activities result in up to 200 arrests each year. It also helps to locate missing persons.
Rabbi Herschel Gluck, the president of Shomrim in north and east London, said the group was delighted by Sir Bernard's endorsement.