It became one of the most successful drama shows on British television.
Rees starred as the spirited servant Demelza, who married Cornish tin mine owner Ross Poldark.
Something of a Downton Abbey of its day, and a contemporary of ITV's popular Upstairs Downstairs, up to 15 million viewers tuned into the BBC's Sunday evening costume drama.
A story of love and greed among sweeping landscapes, Poldark was set in the 18th Century and based on books by Winston Graham. It ran for two series between 1975 and 1977.
Co-starring Robin Ellis and Ralph Bates, it was shown in 22 countries.
Fellow Welsh actress Ruth Madoc told the BBC: "Angharad was a lovely, gentle woman and very pretty.
"Poldark was a landmark series which everyone remembers so well."
Before the TV series which made her name, Rees had appeared in the 1972 film Under Milk Wood with fellow Welsh actors Richard Burton and Sian Phillips, along with Hollywood star Elizabeth Taylor, and was nominated for a best newcomer award for her role in the film Moments (1974) with Keith Michell.
An acclaimed acting career on stage, screen and radio followed.
TV credits included Dennis Potter's Joe's Ark, Remington Steel, a BBC adaptation of Shakespeare's As You Like It and Trainer, a drama series set in the world of horse racing.
She also appeared in the cult horror film Hands of the Ripper and plays such as A Winter's Tale, Richard II, Romeo and Juliet and Hamlet.
For her radio work, she won the Prix Italia for Florent and the Tuxedo Millions in 1982 and was nominated for a best actress award in 1985.
However, she turned her back on acting when her eldest son Linford was killed in a car crash on the M11 in Essex in 1999, aged 26.
At the time, Rees and husband, Dynasty actor Christopher Cazenove, said they were "devastated".
Linford had recently gained a postgraduate degree in philosophy from Cambridge.
Speaking to the South Wales Echo newspaper two years later, Rees said she was "distraught" following Linford's death and threw herself into her "therapeutic" passion for jewellery design.
"I was about to open the shop when my son died," she told the newspaper.
"I became very reclusive. I used to go there every day and work. It was a creative thing and I could lose myself in it."
Her talent led to a successful fine jewellery business, with a shop in Knightsbridge. Her pieces featured in the film Elizabeth - The Golden Age.
It wasn't her first venture in the business world.
In the early nineties, Rees set up her own company to teach relaxation techniques, helping executives, sports stars and academics.
"I like having something on the go. I'm not a lady who lunches," she said in the interview.
After her divorce from Casanove, who died in 2010, she married David McAlpine, of the construction family in 2005.
Despite stepping away from the acting spotlight, she remained an active supporter of the arts.
She also did poetry readings and recited at the gala opening of the Welsh assembly in Cardiff in 1999.
Although born in London, Rees moved to Cardiff as a baby with her Welsh parents, growing up in the suburb of Rhiwbina and attending the local infants school.
Her late father Professor Linford Rees was an eminent psychiatrist, originally from the Burry Port area of Carmarthenshire, while her late mother Catherine was from the Swansea Valley.
Rees maintained the link with the city she grew up in by becoming an honorary fellow of Royal Welsh College of Music and Drama.
Ruth Madoc added: "I knew her very well socially back in London and we worked together from time to time.
"We did a poetry reading in the Grand Theatre in Swansea about 12 years ago.
"I haven't seen her for some time and hadn't realised she was so ill."
She is survived by her husband, and her son Rhys, 35.
Her family released a statement saying they were "deeply saddened" to announce her death "after a long battle with pancreatic cancer".
"She will be greatly missed by her family and friends," they added.
Welsh actress Angharad Rees, who has died of cancer at the age of 63, was one of the best-known faces of the 1970s thanks to her role in Poldark.