Withers was born in Karachi, in British India (now in Pakistan) to Edgar Withers, a captain in the Royal Navy, and a Dutch-German mother, Zitette. She acquired the name "Googie" (Little Pigeon) at a young age from her ayah (nanny). As a child, she learned Urdu.
Her father left the Royal Navy to manage a foundry in Birmingham, England, and Googie was sent to a boarding school near Dover.
She began acting at the age of twelve. A student at the Italia Conti Academy of Theatre Arts, she was a dancer in a West End production when she was offered work as a film extra in Michael Powell's The Girl in the Crowd (1935). She arrived on the set to find one of the major players in the production had been dismissed, and she was immediately asked to step into the role in her place.
During the 1930s, Withers was constantly in demand in lead roles in minor films and supporting roles in more prestigious productions. She was in Windfall (1935), and was an extra in Powell's The Girl in the Crowd (1935) but wound up playing the second female lead.
Powell used her a third time in The Love Test (1935) and she had the lead in All at Sea (1935). Withers supported in Dark World (1935), King of Hearts (1936), and Accused (1936). Her Last Affaire (1936) was her fourth film with Powell.
Withers followed it with She Knew What She Wanted (1936), Crown v. Stevens (1936) (directed by Powell), Crime Over London (1936), Pearls Bring Tears (1937), Action for Slander (1937), and Paradise for Two (1937).
She had the lead in You're the Doctor (1938) and was back to support for Kate Plus Ten (1938). Her best known work of the period was as one of Margaret Lockwood's friends in Alfred Hitchcock's The Lady Vanishes (1938).
Withers kept in support roles in Paid in Error (1938) and Strange Boarders (1938). She was in a Will Hay film Convict 99 (1938) and supported Jack Buchanan in The Gang's All Here (1939). Then she appeared in crime films Murder in Soho (1939) and Dead Men are Dangerous (1939).
She supported George Formby in Trouble Brewing (1939) and Tommy Trinder in She Couldn't Say No (1939). She was in a Robert Montgomer film Busman's Honeymoon (1939) and was reunited with Buchanan in Bulldog Sees It Through (1940). She was still supporting comics in Back-Room Boy (1942) with Arthur Askey.
Among her successes of the 1940s, and a departure from her previous roles, was the Powell and Pressburger film One of Our Aircraft Is Missing (1942), a topical World War II drama in which she played a Dutch resistance fighter who helps British airmen return to safety from behind enemy lines.
Powell and Pressburger then used her in a film they produced but did not direct, The Silver Fleet (1943). She played Helen, a significant second lead in the Clive Book directed 1944 comedy On Approval.
Withers was in They Came to a City (1945) directed by Basil Dearden. She was one of several stars in Dead of Night (1945).
Withers was given a star part in Pink String and Sealing Wax (1945). It was well received and Withers was given the title role in The Loves of Joanna Godden (1947), which was a hit. In the cast was John McCallum who Withers later married. They remained married until McCallum died in 2010.
Withers was then in It Always Rains on Sunday (1948) which was one of the biggest hits of the year. In 1948 British exhibitors voted her the 8th most popular British star in the country.
Withers had a support role in the hugely popular Miranda (1948) with McCallum. Withers then made two comedies, both directed by Ralph Thomas: Once Upon a Dream (1949) and Traveller's Joy (1949). She had a good support role in Night and the City (1950) opposite Hollywood star Richard Widmark.
Withers took 13 months off for the birth of her first child then returned to play a doctor in White Corridors (1951), one of the most popular films of the year in Britain. She was one of many cameos in The Magic Box (1951) and was in a play Winter Journey.
Withers made three films with her husband, Derby Day (1952), Devil on Horseback (1954), and Port of Escape (1956).
Withers first toured Australia in the stage play Simon and Laura. When McCallum was offered the position running J.C. Williamson theatres, they moved to Australia in 1959. Withers starred in a number of stage plays, including Rattigan's The Deep Blue Sea, Desire of the Moth, The First 400 Years (with Keith Michell), The Circle, A. R. Gurney's The Cocktail Hour, Time and the Conways, The Importance of Being Earnest, Beekman Place (for which she also designed the set) (1965), The Kingfisher, Stardust, Chekhov's The Cherry Orchard and Wilde's An Ideal Husband for the Melbourne Theatre Company; both productions toured Australia. They appeared together in the UK in The School for Scandal at the Duke of York's Theatre in London's West End and on the subsequent British Council tour of Europe in 1983–84 and in W. Somerset Maugham's The Circle at the Chichester Festival Theatre.
Withers starred on Broadway with Michael Redgrave in The Complaisant Lover and in London with Alec Guinness in Exit the King.
Withers returned to films with the lead in Nickel Queen (1971), directed by McCallum.
She was in The Cherry Orchard (1974) on Australian tv.
During the 1970s, she appeared as Faye Boswell, the governor of a women's prison, in the television series Within These Walls. Because Within These Walls had been a moderate success in Australia, she was approached by producers to play the role of the Governor of the Wentworth Detention Centre in the later series Prisoner, a job which she declined.
Withers starred in the BBC adaptation of Hotel du Lac (1986), which was followed a year later by another BBC production of Northanger Abbey.
In 1989 she appeared at Brighton in England in The Cocktail Hour alongside her husband John and her daughter, Joanna - the play a success from New York starring Nancy Marchand, the previous year. In 1990, she appeared in ITV's adaptation of Ending Up. Her last screen performance was as the Australian novelist Katharine Susannah Prichard in the film Shine (1996), for which she and the other cast members were nominated for a Screen Actors Guild award for "Outstanding performance by a cast".
In 2002, aged 85, Withers appeared with Vanessa Redgrave in Oscar Wilde's Lady Windermere's Fan in London's West End.
In October 2007, aged 90 and 89 respectively, Withers and McCallum appeared in an extended interview with Peter Thompson on ABC TV's Talking Heads programme.
Withers died on 15 July 2011 at her Sydney home, aged 94. Her husband John McCallum predeceased her on 3 February 2010.
Withers was appointed an Honorary Officer of the Order of Australia (AO) for services to drama, in the 1980 Australia Day Honours List. In the 2001 Queen's Birthday Honours List (UK), she was named a Commander of the Order of the British Empire (CBE). Withers was a JC Williamson Award recipient for lifetime achievement in 1999. In 1992 Googie Withers and John McCallum were founding patrons and active supporters of the Tait Memorial Trust in London. A Charity established by Isla Baring OAM, the daughter of Sir Frank Tait of JC Williamson's to support young Australian performing artists in the UK.
She was the subject of This Is Your Life in 1971 when she was surprised by Eamonn Andrews.