Thatcher was born in Hammersmith, London, on 15 August 1953. She and her twin brother, Mark, were born six weeks prematurely by C-section. According to Margaret Thatcher, her husband Denis Thatcher responded to seeing their children for the first time by saying, "My God, they look like rabbits. Put them back." Thatcher's mother was selected for Finchley in 1958 and was elected as a Member of Parliament in 1959.
In 1960, Thatcher was sent to Queenswood School, a girls' boarding school near Hatfield, Hertfordshire, before attending St. Paul's Girls' School. She graduated with a law degree from University College London, before moving to Australia in 1977 to begin a journalism career. While she was there, her mother was elected Prime Minister. Thatcher later said, "You need quite good shock absorbers and a sense of humour to be the Prime Minister's child."
Thatcher began her career as a journalist in Australia, working on the Sydney Morning Herald from 1977 to 1979. She became a TV reporter at Channel Seven, also in Sydney, and later a reporter on its news morning show, 11AM. On her return to Britain, she worked as a presenter for LBC, BBC Radio 4, TV-am and wrote travel articles for The Daily Telegraph. Due to her mother's high-profile political position, many newspapers refused to publish work with her byline.
Her first book, Diary of an Election: with Margaret Thatcher on the campaign trail, was published in 1983. Her second book, a collaboration with tennis player Chris Evert (Mrs Lloyd) called Lloyd on Lloyd, was released three years later. It became Thatcher's first best-seller.
Later publications included a 1996 best-selling biography of her father, Below the Parapet. In 2003, Thatcher produced a Channel 4 documentary about him called Married to Maggie. Thatcher captured the only public interview Denis Thatcher gave in his lifetime; he died shortly after its release. Thatcher's freelance career has included contributing articles to magazines and papers as well as television work.
From 2006 to 2009, Thatcher was a freelance contributor to the BBC One magazine programme The One Show, making filmed reports and joining the presenters and guests in the studio for discussions. On 3 February 2009, British media reported that during the 2009 Australian Open Thatcher had, in a conversation in the show's green room, referred to a black tennis player, reportedly Jo-Wilfried Tsonga, as a golliwog.
According to The Times, Thatcher called Tsonga "half-golliwog" and "the golliwog Frog". Presenter Adrian Chiles, comedian Jo Brand, journalists and several guests were with Thatcher when she made the remark. The BBC stated that Thatcher would not work again on The One Show unless she made a more sincere apology. Thatcher refused, saying "I stand by what I said. I wasn't going to apologise. I never meant it in a racist way. It was shorthand. I described someone's appearance colloquially—someone I happen to greatly admire."
In November 2005 Thatcher was selected to appear with a number of fellow celebrities on the ITV television show I'm a Celebrity...Get Me Out of Here!. The format of the show meant that she would be forced to spend at least a week in the Australian rainforest with a minimal supply of food in basic living conditions.
She had to undergo one of the more infamous "Bushtucker Trials" during her stay in the jungle — which saw her eat jungle bugs and kangaroo testicles as a challenge to earn food for her fellow celebrities. Ultimately, she emerged as the fifth series winner and second 'Queen of the Jungle'.
Thatcher appeared on Living TV's Most Haunted on 13 February 2007 as a celebrity guest alongside presenter Yvette Fielding and medium David Wells as well as Joanne Gregory to search for paranormal activity at Tatton Hall in Cheshire.
In 2007, Carol Thatcher travelled to the Falkland Islands and Argentina for the documentary Mummy's War, in order to explore the legacy of the Falklands War. Whilst receiving a highly positive reception from the pro-British islanders (who regard her mother as a heroine), her reception in Argentina provoked protests and demonstrations (including the cry "Your mother is a war criminal!"). During her stay in Argentina, she met a group of mothers who lost their sons during the conflict and stated, "We were fighting a war; we won, you lost," and reminded them that it was their country that invaded the islands, thus initiating the conflict. The interview ended with one of the women claiming that "God will punish her (Margaret Thatcher)".
Thatcher had a relationship with Jonathan Aitken, which ended in 1979. As this happened just after the Conservatives won the general election, Aitken's breaking up with Thatcher is alleged to have been the reason for his being bypassed for a ministerial career; Thatcher's mother, the Prime Minister at the time, reportedly told cabinet colleagues that she was "damned" if she was going to give a job to a man "who had made Carol cry".
Thatcher lives with ski instructor Marco Grass in Klosters-Serneus, Switzerland.