The 54-year-old had previously denied seven counts of indecent assault and two counts of sexual touching without consent, against six female complainants between 1991 and 2014.
Six additional counts of indecent assault - relating to three different girls aged under 16 in 1987 and 1988 - were put to him at Westminster Magistrates' Court today.
Dressed in a blue suit, white shirt and striped tie, he spoke only to confirm his identity and plead not guilty to the new charges.
Fox is due to stand trial on the original charges at magistrates court on November 5.
Another legal hearing on October 6 will determine where the trial for the new alleged offences, said to have occurred in Euston, will take place.
At a previous hearing the prosecution submitted the allegations against Fox show a "consistent and determined pattern of sexual predatory behaviour".
One of the allegations is that he forced himself on a girl as young as 13, and attacked a teenager at a popular theme park.
One complainant alleges that he repeatedly assaulted her at Capital Radio's studios in London's Leicester Square.
Two other women claim to have been sexually touched by the radio presenter at Magic FM's premises in Winsley Street in central London, between January 2003 and August 2014.
Fox is further accused of assaulting two different girls at a summer 1991 motor show in Bromley, south-east London.
He allegedly forced his tongue in to the mouth of a girl aged around 13 or 14 after she asked for a photo with him.
A second teenager claims she was abused by Fox in a similar manner, but that he also put his hand up her skirt.
A third youngster, who was under the age of 16 at the time, alleges that she was attacked in April 1996 after asking Fox for a photo while at Chessington World of Adventures.
Four of the alleged indecent assaults are said to have taken place at Capital Radio in 2003.
It is alleged that on one occasion he put his arms around a woman and squeezed her breasts, regularly touched her bottom, and that one incident involved him simulating sex with the complainant.
During one of the alleged assaults at Magic FM, Fox is said to have walked up behind the complainant, kissed her shoulder and then told her she looked like she tasted "good".
Fox, from Fulham, south-west London, was first arrested in September last year, then again in December and March.
He rose to fame presenting the chart show on Capital Radio, and was a judge on Pop Idol between 2001 and 2003 alongside Simon Cowell, Pete Waterman and Nicki Chapman.
He was released on bail on condition he does not contact any of the complainants.