The 84-year-old appeared at London's Southwark Crown Court, accompanied by his wife Alwen, who looked on from the public gallery with other family members as he sat in the glass-walled dock.
Wearing a grey suit and a pink shirt with blue stripes, and a red and black tie, Harris, from Bray in Berkshire, listened to proceedings through a hearing loop.
A panel of 12, made up of six men and six women, along with three extras, two men and one woman, were chosen from a pool of more than 20 potential members.
Harris stood at the front of the dock as the process took place, and the indictment was read out.
Mr Justice Sweeney told the jurors: "I am the judge of the law, likewise you are the judges of the facts. As judges of the facts, your duty, pooling your common sense and experience of life, is to assess the witnesses and the other evidence that is put before you in the trial, and in due course to decide the relevant facts and thereby, having applied my directions of law, to reach a verdict according to the evidence.
"A number of duties follow from your role as judges of the facts. It's your duty to try the case on the evidence that you hear in this courtroom and nothing else."
He said jurors have duties, including not allowing themselves to be influenced "by any external matter", including media coverage.
They should not discuss the case with anyone else, should not post entries on social networking sites about the trial, or try to research the case themselves.
Harris is accused of 12 counts of indecent assault on four alleged victims, the youngest of whom was seven or eight and the oldest 19, between 1968 and 1986.
The clerk of the court read the indictment to the jury. The allegations are:
l Count 1 - indecent assault of a girl aged seven or eight on an occasion between January 1968 and January 1970;
l Count 2 - the same offence on a girl aged 14 between January 1975 and January 1976;
l Counts 3 and 4 - the same offence on a girl aged 12 to 15 between December 1978 and April 1981;
l Count 5 - indecent assault of a girl aged 14 to 15 between the same dates;
l Counts 6 to 8 - indecent assault of a girl aged 12 to 15 between the same dates;
l Count 9 - the same offence on a girl aged 19 between January 1984 and January 1985;
l Counts 10 to 12 - the same offence on a girl aged 14 on May 31, 1986.
The former television presenter denies all the counts.
It is expected the prosecution case will open today.