Booth's father was a Wall Street stock broker and her mother an Actress. They moved to New York State after Connie's birth in Indianapolis, Indiana. Booth entered acting and worked as a Broadway understudy and waitress, meeting John Cleese while he was working in New York City. She married Cleese on February 20, 1968.
Booth secured parts in episodes of Monty Python's Flying Circus (1969–74) and in the Python films And Now for Something Completely Different (1971) and Monty Python and the Holy Grail (1975, as a woman accused of being a witch). She also appeared in How to Irritate People (1968), a pre-Monty Python film starring Cleese and other Future Monty Python members; a short film titled Romance with a Double Bass (1974) adapted by Cleese from a short story by Anton Chekhov; and The Strange Case of the End of Civilization as We Know It (1977), Cleese's Sherlock Holmes spoof, as Mrs. Hudson.
In 1971, Booth and Cleese had a daughter, Cynthia, who appeared alongside her father in the films A Fish Called Wanda and Fierce Creatures. Booth and Cleese divorced in 1978. With Cleese, Booth wrote the scripts for and co-starred in both series of Fawlty Towers, even though the two were actually divorced before the second series was finished and aired. Booth's daughter Cynthia married Screenwriter Ed Solomon in 1992.
Booth and Cleese went on to write and co-star in Fawlty Towers (1975 and 1979), in which she played waitress and chambermaid Polly.
Booth played various roles on British television, including Sophie in Dickens of London (1976), Mrs. Errol in a BBC adaptation of Little Lord Fauntleroy (1980) and Miss March in a dramatisation of Edith Wharton's The Buccaneers (1995). She also starred in the lead role of a drama called The Story of Ruth (1981), in which she played the role of the schizophrenic daughter of an abusive father, for which she received critical acclaim. In 1994, she played a supporting role in "The Culex Experiment", an episode of the children's science fiction TV series The Tomorrow People.
Booth ended her acting career in 1995. After studying for five years at London University, she began a career as a psychotherapist, registered with the British Psychoanalytic Council.
Booth married John Lahr, author and former senior drama critic of The New Yorker, in 2000. They live in north London.
For 30 years Booth declined to talk about Fawlty Towers until she agreed to participate in a documentary about the series for the digital channel Gold in 2009.
