Lewis was born in Chicago, Illinois, and was a graduate of the University of Chicago, where she was a member of a literary circle that included Glenway Wescott, Elizabeth Madox Roberts, and her future husband Yvor Winters. She was an active member of the University of Chicago Poetry Club. She taught at both Stanford University in California, and the University of California at Berkeley.
She wrote The Wife of Martin Guerre (1941) which is the tale of one man's deception and another’s cowardice. Her first novel was The Invasion: A Narrative of Events Concerning the Johnston Family of St. Mary's (1932). Other prose works include The Trial of Soren Qvist (1947), The Ghost of Monsieur Scarron (1959), and the volume of short fiction, Good-bye, Son, and Other Stories (1946).
Lewis was also a poet, and concentrated on imagery, rhythms, and lyricism to achieve her goal. Among her works are The Indians in the Woods (1922), and the later collections Poems, 1924–1944 (1950), and Poems Old and New, 1918–1978 (1981). She also collaborated with Alva Henderson, a composer for whom she wrote three libretti and several song texts.
- The Invasion: A Narrative of Events Concerning the Johnston Family of St. Mary's (1932)
- The Wife of Martin Guerre (1941)
- Good-bye, Son, and Other Stories (1946)
- The Trial of Soren Qvist (1947)
- The Ghost of Monsieur Scarron (1959)
- Against a Darkening Sky (1985)
- The Indians in the Woods. Published by Monroe Wheeler, as Manikin Number One, Bonn, Germany, n.d. .
- The Wheel in Midsummer Lynn, Mass, The Lone Gull, 1927.
- The Earth-Bound' Aurora, New York, Wells College Press, 1946
- Poems 1924 – 1944 Denver, Alan Swallow, 1950
- The Ancient Ones Portola Valley, California: No Dead Lines, 1979
- The Indians in the Woods 2nd edition with new preface, Palo-Alto California, Matrix Press, 1980.
- Poems Old and New 1918 – 1978 Chicago/Athens, Ohio: Swallow Press / Ohio University Press 1981
- Late Offerings Florence, Ky, Robert L. Barth, 1988
- Janet and Deloss: Poems and Pictures San Diego, Brighton Press 1990
- The Dear Past and other poems 1919 – 1994 Edgewood Ky, Robert L. Barth, 1994
- The Selected Poems of Janet Lewis thens Ohio, Swallow Press / Ohio University Press, 2000, ISBN 978-0-8040-1023-8.
- Thomas, Robert McG., Jr. (December 5, 1998). "Janet Lewis, 99, Poet of Spirit and Keeper of the Hearth, Dies (obituary)". The New York Times. Retrieved July 11, 2010.
- Davis, Dick (December 15, 1998). "Obituary: Janet Lewis". The Independent. Retrieved July 11, 2010.
- "Janet Loxley Lewis". poetryfoundation.org. Retrieved 14 September 2015.
- Stanford University Libraries & Academic Information Resources—American Literary Studies: Janet Lewis Papers 
- Yale University Beinecke Rare Book and Manuscript Library—Kathleen Foster Campbell Papers 
- "Book of Members, 1780–2010: Chapter W" (PDF). American Academy of Arts and Sciences. Retrieved July 29, 2014.
- Kathleen Foster Campbell Papers at Yale University Beinecke Rare Book and Manuscript Library