Eleven officers are being stationed in schools in Southwark - the first starts officially on Monday in Archbishop Michael Ramsey school, just half a mile away from the spot where Damilola Taylor, 10, died.
Rod Jarman, borough commander for Southwark, said a few young offenders committed many crimes.
"Very often the victims are other schol-age children," he said. "We hope that by having officers in schools we will be able to offer a more approachable policing service."
David Hart, general secretary of the National Association of Head Teachers, said: "Children must inform the head first of any alleged crimes that take place during the school day."
Wendy Parmley, head at Archbishop Michael Ramsey school, said: "I hope it deters people from thinking that they can come here and mug our pupils and staff."