Three of the allegations against the 53-year-old Magic FM presenter, known as Dr Fox , are said to have happened in the 1990s, while six others are said to have occurred in 2007.
In December he was questioned by officers over four separate sexual assault allegations.
A statement from the Metroplitan Police said: "Neil Fox, 53 (12.6.61) of Fulham SW6 has been charged with nine offences involving six victims, three of which were juveniles at the time of the alleged offences."
Fox is due to appear on bail at Westminster Magistrates' Court on April 16 charged with one count of indecent assault on a female aged under 14 and two counts of indecent assault on a female aged under 16.
These offences are alleged to have taken place between 1991-1996 and relate to three separate victims who were juveniles at the time of the alleged offences.
He has also been charged with four counts of indecent assault on a female over 16 contrary to Sexual Offences Act 1956 and two counts of sexual assault on a female contrary to Section 3 Sexual Offences Act 2003.
These offences are alleged to have taken place between 2003 and 2014 and relate to three separate victims.
Fox was first arrested in connection with the inquiry last September.
The former Pop Idol judge, who is currently suspended from his radio show, was arrested again in December over three alleged sexual assaults involving different women.
Fox, who uses the nicknames Dr Fox and Foxy, began his career in local radio before moving to Radio Luxembourg and then London's Capital Radio in the late 1980s.
He presented various slots there and in 1993, landed the job of presenting the Sunday afternoon Network Chart Show, later known as the Pepsi chart.
His big TV break, which brought him to a wider audience, was as a judge on ITV talent show Pop Idol between 2001 and 2003 alongside Simon Cowell, Pete Waterman, and Nicki Chapman.
Fox later appeared in the BBC Three sketch show The Wrong Door.
He left Capital in 2005 and joined Magic 105.4, where he presented the breakfast show until being suspended following his arrest last September.