Italian was her first language and the language in which she corresponded with her father. She studied ballet while she was a teenager, becoming good enough to train with Isadora Duncan. She started to show signs of mental illness in 1930, around the time she began casually dating Samuel Beckett. Her deteriorating mental state caused him to call off the relationship, and in 1934, Carl Jung took her in as a patient. Soon after, she was diagnosed with schizophrenia at the Burghölzli psychiatric clinic in Zurich. She was placed in an institution in Ivry-sur-Seine, France, in 1935.
In 1951 Lucia was sent to St Andrew's Hospital in Northampton, where she was visited at times by Beckett. She suffered a stroke in 1982 and died December 12 of that year.  She is buried in Kingsthorpe Cemetery.
Her mental state, and documentation pertaining thereto, is the subject of a recent study by Carol Shloss, who believes Lucia to have been her father's muse for Finnegans Wake. The study makes heavy reference to the letters between Lucia Joyce and her father, and became the subject of a copyright misuse suit by the James Joyce estate. On 25 March 2007, this litigation was resolved. Her life was the subject in 2004 of a West End play, Calico, written by Michael Hastings, and in the 2012 graphic novel, Dotter of Her Father's Eyes.
- Shloss, Carol Loeb. Lucia Joyce: To Dance in the Wake. Farrar, Straus, and Girous, New York, 2003. ISBN 0-374-19424-6.
- Patry, William (2006), "The Patry Copyright Blog: Copyright's Wake". Retrieved June 13, 2006. (concerning research done on Lucia as Joyce's muse)
- Tracey, Patrick (2008). Stalking Irish Madness: Searching for the Roots of My Family's Schizophrenia. Random House Digital, Inc. p. 162. ISBN 9780553805253.
- Beja, Morris (1992). James Joyce: A Literary Life. Columbus, Ohio: Ohio State University Press. p. 125.
- Joyce letters court case settled. B.B.C., 2007-03-25.
- Scholar, James Joyce estate settle copyright dispute. First Amendment Center/Associated Press, 2007-03-27.
- Cooke, Rachel (27 January 2012). "Dotter of Her Father's Eyes by Mary M Talbot and Bryan Talbot – review". The Guardian. Retrieved 13 July 2012.
- Lucia Joyce. Collection of articles and reviews.
- The Mystery of the Muse: Anna Livia Plurabelle Uncovered
- Resolution of the litigation. Retrieved December 9, 2007.