Catherine Carswell, née Macfarlane, was born in Glasgow, Scotland, and attended the New Park School for Girls as well as evening classes at the Glasgow School of Art. In 1901, she enrolled at the University of Glasgow to study English literature. Although she achieved the academic outcomes, she could not be awarded a degree because she was a woman. She then spent two years studying music at the Hoch Conservatory in Frankfurt, Germany before returning to Glasgow intent on a career in the arts.
In 1904, she met Herbert Jackson, a Boer War veteran and artist, and married him after a whirlwind courtship of one month. The following year, he threatened to kill her and was confined to a mental institution for the rest of his life. She gave birth to their daughter the following October. Her marriage to Jackson was dissolved on the grounds that she did not know about his mental illness when she married him. She went to work as a critic for the Glasgow Herald and began a lengthy affair with the artist Maurice Greiffenhagen, 17 years her senior. During this time, she began to participate in literary circles and later became a close friend of D.H. Lawrence.
She moved to London, and in 1915 remarried to Donald Carswell, with whom she had a son. She became assistant drama critic for The Observer and published her first novel, Open the Door! in 1920. Two years later, she published her other novel, The Camomile. She finally achieved fame with a controversial biography of Robert Burns published in 1930. Later in the 1930s, she edited three anthologies and wrote a biography of Italian Renaissance poet Giovanni Boccaccio called The Tranquil Heart (1937).
She wrote a two-volume biography of John Buchan together with his widow Lady Tweedsmuir, The Clearing House (1946) and John Buchan by His Wife and Friends (1947).
After her death, her son John Carswell edited and published her autobiographical writings as Lying Awake: An Unfinished Autobiography (1950). Some of her works were rediscovered and republished in the 1980s, and she's now considered a major Scottish writer of the early 20th century.