Coyne was born in Springs, South Africa in 1965. She was a member of the Capab drama group for seven years after training as an actor. She also worked at a rhinocerous and elephant sanctuary in Kenya for four years.
In 2009, Coyne appeared in The Adventures of Pinocchio, a pantomine by Janice Honeyman, as Katarina the Cat. She also authored the book, Who Moved My Ladder? The Working Woman's Guide to Success.
Coyne was best known to South Africans for her role as the presenter of The Weakest Link. Her appearance, hair, dress and style of speaking to contestants were modelled on Anne Robinson, who hosted the British version of the show. Coyne beat approximately 500 people for The Weakest Link role. She was flown to London in 2003 to train with Anne Robinson before the South African version of the show was launched.
Fiona Coyne died at her home in Fish Hoek, South Africa, on August 18, 2010, of a suspected suicide at the age of 45. She had recently divorced her husband, Willie Fritz, after 22 years of marriage. She had reportedly left notes for her housekeeper, Zoleka Shumani, and her family. A funeral was held at St. Peters Catholic church in Strand, Western Cape.