She was born in Broadgreen Hospital to Gladys Norbury and Edward Mooney. She initially grew up in Liverpool on a council estate called The Green on Queen's Drive. She passed her eleven plus and went to Aigburth Vale Girls’ High School (merged with another school to become Calderstones School in 1989). She moved to Wiltshire at the age of fourteen, when her parents bought their first house. She then attended school in Trowbridge, Wiltshire, at Trowbridge Girls' High School (merged with a boys' grammar school to become the comprehensive John of Gaunt School in 1974). She passed eight O levels and took English, Latin and Art at A level. She had tried to gain entry to the University of Oxford but at that time nobody from her girls' grammar school had achieved that. So she went to London and obtained a first class degree in English Language and Literature from University College London in 1969. She met her first husband and philosophy student, Jonathan Dimbleby, there when both working on the student magazine called Pi Magazine and they married in February 1968 in Kensington after knowing each other for four months.
Giving up her idea of postgraduate work, Mooney became a journalist in 1969, contributing first to the Bath Chronicle and the Times Educational Supplement (whilst teaching part time in Bath) then got her first job on Nova Magazine as Assistant to the Editor. In the early seventies, Mooney wrote for the New Statesman, the Daily Telegraph Magazine, Cosmopolitan and many others. She has been a regular columnist for The Times (from 2005-7), The Sunday Times (from 1982-3) and The Listener (from 1984-6). From 1970-9 she was a freelance journalist. (Her reference to Margaret Thatcher in Nova magazine in 1973 as a 'possible future Prime Minister' is believed to have been the first suggestion of its kind in the media.) As well as her fiction (see below) Mooney has written many books, including 'Bel Mooney's Somerset' (1989) and a memoir about love, loss, recovery - and dogs: 'Small Dogs Can Save Your LIfe' (2010).
Having made her name as a journalist, columnist, and broadcaster, she turned her hand to writing fiction for adults and children. She is the author of the best-selling 'Kitty and friends' series of stories for young girls, including I Don’t Want To! and So What, which were inspired by her own daughter, Katherine, or Kitty as she is known. She then went on to write a series of six books inspired by her small dog Bonnie, with titles like 'Big Dog Bonnie and 'Brave Dog Bonnie.'
She was a regular presenter on BBC Radio 4 from 1982 until 2008, notably as presenter of Devout Sceptics, a programme devoted to public figures' private beliefs, not necessarily agnostic or atheistic, as the name might suggest. She also made many series for Channel 4 (for example 'Mothers By Daughters') and BBC2 (for example, 'Grief') and one-off documentaries on people like Ellen Wilkinson MP and Dora Russell. As the 'story' itself, interviewed many times of radio and television, Mooney has been active in ecological campaigning. In particular she was involved, like her former husband, in the campaign against the Batheaston Bypass in the mid 1990s. During the eighties and nineties she wrote six novels and made many programmes for television and for Radio 4.
In June 2007 she began writing a weekly column for the Saturday edition of the Daily Mail, advising readers on emotional and relationship issues, and she contributes other comment articles to the paper.
She has honorary degrees from the University of Bath in 1998 and Liverpool John Moores University in 2002. 'Devout' Sceptics won a Sandford St Martin Trust award for religious broadcasting, and one children's novel 'The Voices of Silence' won a New York Public Library citation and was shortlisted for a Gold Medal in the State of California.
Mooney was married to the television journalist Jonathan Dimbleby for thirty-five years where they lived on an organic farm. The couple separated in 2004 after his affair with opera singer Susan Chilcott; since 2006 they have been divorced. They have two adult children, Kitty (born 1980), a freelance journalist and Daniel (born 1974), a television producer/director. On September 8, 2007, Mooney married Robin Allison-Smith, a freelance photographer, with whom she lives on the outskirts of Bath.