The police said the 28-year-old journalist was being questioned at a North London police station about alleged computer hacking relating to the identification of a previously anonymous blogger in 2009.
The police did not identify the arrested journalist as per normal procedure, but the BBC named him as Patrick Foster.
He is the 11th person to be arrested under Operation Tuleta, which is investigating criminal breaches of privacy, including computer hacking.
The police said he had been arrested "for suspected offences under the Computer Misuse Act 1990 and suspected conspiracy to pervert the course of justice, contrary to the Criminal Law Act 1977".