The 83-year-old, from Bray in Berkshire, appeared at Southwark Crown Court and pleaded not guilty to 12 counts, alleged to have taken place between 1968 and 1986.
Wearing a blue jacket, white shirt and red tie, he stood in the dock and replied "not guilty" to each of the charges as they were read by the clerk.
He was accompanied by his wife Alwen, who arrived at court in a wheelchair, and his daughter Bindi.
The allegations of indecent assault Mr Harris faces include six counts on a girl aged 15 between April 5, 1980 and April 4, 1981; one on a woman aged 19 between January 1, 1984 and January 1, 1985; three on a 14-year-old girl on May 31, 1986; one on a girl of seven or eight between January 1, 1968 and January 1, 1970; and one on a girl aged 14 between January 1, 1975 and January 1, 1976. They relate to four alleged victims.
He has yet to be arraigned on four counts of making an indecent image of a child.
Mr Harris is due to face trial on April 30.
The Australian, his family and security guards left the court in front of a scrum of waiting journalists. They made no comment.
Meanwhile, comedian Freddie Starr has been arrested for a third time over alleged sexual offences.
He was told that he faces a further claim when he attended a police station in Warwickshire by appointment.