The woman, who claims the entertainer began abusing her when she was 13, said he appeared to get "a thrill" out of carrying out assaults while his daughter was present.
She told Southwark Crown Court, London, she kept the alleged abuse secret for years, frightened nobody would believe her. She said she finally confessed to her parents in her late 20s.
The court was told she later told Mr Harris's daughter, Bindi,when the star's daughter asked her, "Has he touched you?".
Mr Harris, 84, is accused of 12 counts of indecent assault - seven of which relate to the woman - between 1968 and 1986. Wearing a dark grey suit with a pink shirt and striped, multi-coloured tie, he remained impassive as the alleged victim gave evidence. Mr Harris's wife, Alwen, also showed no visible emotion.
Giving evidence from behind a curtain, the woman told the court Harris first abused her during a holiday in Hawaii in 1978 when she was 13, giving her a "creepy" hug before touching her sexually when she was standing in a towel.
She told the jury of six women and six men: "The way he hugged you and touched you all over, it was cringey.
"The way Rolf folded himself around you, he was a big man ... he enfolded you in his arms and then touched you up and down over your body. He'd go 'ooh'."
The woman outlined a series of alleged indecent assaults carried out by the star in his home, and in hers, even when her parents were downstairs.
She said Harris appeared to get a thrill out of indecently assaulting her while his daughter was asleep in the same room. "He didn't feel inhibited, I think he got a thrill out of it," the alleged victim told the jury.
Asked why she thought this, she said: "By the look on his face, looking over at Bindi and just carrying on."
She became anxious and panicky after the alleged abuse began, and began drinking, "swigging" glasses of gin and tonic water when her parents were not around, she said.
Four of the counts on the indictment against Mr Harris allege he indecently assaulted the girl when she was 15; two relate to allegations he performed oral sex on her against her will before she was 16; and one relates to an occasion when he allegedly indecently assaulted her in a swimming pool when she was 19.
The court heard the performer also touched himself sexually in front of the alleged victim.
The woman, who said she left school at 16, said she had started to become "distant" and felt she was to blame.
Asked about another alleged assault in a swimming pool at the entertainer's home in Berkshire when she was 19, she said: "I let him do it, I didn't want him to, but I let him do it like all the other times."
The woman told the court that from the age of about 20 until she was 28 she had a number of consensual sexual encounters with Harris, and "felt dead".
The court heard that, whilst drunk, she wrote to Mr Harris, then a presenter on TV's Animal Hospital, asking for £30,000 to help her boyfriend save his bird sanctuary. She denied in court threatening to go to the press unless it was paid.
The trial continues.