The man was arrested on suspicion of conspiracy to intercept voicemail messages and attempting to pervert the course of justice.
The arrest took place by appointment at a north London police station; the man is in police custody.
He has been bailed to a date in mid January 2012.
He was arrested by officers from Scotland Yard's fresh investigation into phone hacking, Operation Weeting.
On Tuesday, a 71-year-old Stuart Kuttner, an ex-News of the World managing editor, was rearrested and bailed as part of the phone-hacking probe.
Mr Kuttner was originally arrested on 2 August on suspicion of conspiring to intercept communications and corruption, and bailed.
He has now been bailed to a date in September, the Metropolitan Police said.
The Met's Operation Weeting is investigating illegal hacking of the mobile phone voicemails of public figures by the now-defunct News of the World newspaper.
The latest arrest is the 15th to be made on suspicion of phone hacking since Operation Weeting was launched in January. It happened just after midday.
BBC home affairs correspondent Tom Symonds said the age of the arrested person suggested someone more junior compared to some of the more senior executives who have been arrested by the police so far.
It is a long-running investigation and there would almost certainly be further arrests, our correspondent added.
Former News International chief executive Rebekah Brooks and ex-Downing Street communications chief Andy Coulson are among those who have already been arrested as part of the inquiry.
The scandal has led Met Police Commissioner Sir Paul Stephenson and Assistant Commissioner John Yates to resign, and the News of the World to close down after 168 years.
A 30-year-old man has been released on bail after being arrested by police investigating phone hacking at the News of the World.