Known for her expert piano as well as her distinctive, operatic voice, which has a three and a half octave range, Galás has been described as "capable of the most unnerving vocal terror. Galás often shrieks, howls, and seems to imitate glossolalia in her performances. Her works largely concentrate on the topics of suffering, despair, condemnation, injustice and loss of dignity. Critic Robert Conroy has said that she is "unquestionably one of the greatest singers America has ever produced", and comparisons are frequently made between her and another singer of Greek origin, Maria Callas.
She has worked with many avant-garde composers, including Iannis Xenakis, Vinko Globokar and John Zorn. She made her performance debut at the Festival d'Avignon in France as the lead in Globokar's opera, Un Jour Comme Un Autre. The work was sponsored by Amnesty International.
Her work first garnered widespread attention with the controversial 1991 live recording of the album Plague Mass (1984 - End of the Epidemic) in the Cathedral of Saint John the Divine in New York. With it, Galás attacked the Roman Catholic Church (and society in general) for its indifference to AIDS using biblical texts. In the words of Terrorizer Magazine, "The church was made to burn with sound, not fire.. Plague Mass was a live rendition of excerpts from her Masque Of The Red Death trilogy which began as a response to and indictment of the effects of AIDS on the "silent class". After production of the trilogy's first volume began, Galás' brother, playwright Philip-Dimitri Galás, contracted HIV. It is important to note that Galás did not begin this work due to her brother's illness. However, this tragic situation inspired the artist to re-double her efforts, resulting in the development of the aforementioned performance. During the period of these recordings, Galás had we are all HIV+ tattooed upon her knuckles; an artistic expression of disillusionment and disgust with the ignorance and apathy surrounding the AIDS epidemic. Her brother, who died during the trilogy's final production, reportedly appreciated her efforts.
In 1994, Galás collaborated with Led Zeppelin bassist John Paul Jones, a longtime admirer of the singer. The resultant record, The Sporting Life, while containing much of Galás's trademark vocal gymnastics, is probably the closest she has ever come to rock music, and is comprised of nearly all original material.
Galás also performs as a blues artist interpreting a wide range of songs into her unique piano and vocal styles, beginning with Let My People Go, from volume 3 of the Masque trilogy, You Must Be Certain of the Devil. This aspect of her work is perhaps best represented by her 1992 album, The Singer, where she covered the likes of Willie Dixon, Roy Acuff, and Screamin' Jay Hawkins while accompanying herself on piano. For that album, she also recorded several traditional songs as well as the rarely heard Desmond Carter-penned version of Gloomy Sunday. Many of the traditionals recorded for The Singer were historically sung by the black slaves of the southern United States. Galás, however, sung these songs for the daily struggle of People With AIDS (PWA's). Galás used many of her selections both within and outside of blues repertoire resulting in numerous song cycles: Reap What You Sow, Malediction and Prayer: Concert for the Damned, Frenzy: Concert for Aileen Wuornos, Burning Hell, La Serpenta Canta, Songs of Exile, Guilty Guilty Guilty, Les chansons malheureuses, Valentine's Day Massacre, and You're My Thrill. Some song selections have sometimes been categorized as "homicidal love songs". She also focuses on the death penalty. The above mentioned "Frenzy: Concert for Aileen Wuornos," was dedicated to the executed serial killer, and features cover versions of Phil Ochs's "Iron Lady" and Hank Williams' "I'm So Lonesome I Could Cry".
Galás has published one book, 1996's The Shit of God (ISBN 185242432X). It contains many of her original writings, and was published because, she says, many people cannot understand her on the records.
In 1997, Galás contributed her voice to the CD Closed on Account of Rabies, a double disc tribute to Edgar Allan Poe with various musicians, including Iggy Pop, Debbie Harry and Marianne Faithfull lending their voice to the tales of the ledgendary horror author. Galás read "The Black Cat" which became the longest recording on the compilation, reaching 36 minutes and 58 seconds.
In 2005, she was awarded Italy’s prestigious Demetrio Stratos International Career Award.
In late 2003, Galás released the album "Defixiones, Will and Testament: Orders from the Dead," an 80-minute memorial tribute to the Armenian, Greek, Assyrian and Hellenic victims of the Turkish genocide. "Defixiones" refers to the warnings on Greek gravestones against removing the remains of the dead.
As of July 2007, Galás continues to tour her latest song cycles. Her newest record, Guilty Guilty Guilty, was released on Mute records on April 1, 2008. You're My Thrill is also set for release on Mute; however, a firm release date has not been made available.
Galás has interpreted poetry by Charles Baudelaire (on The Litanies of Satan), Paul Celan, Pier Paolo Pasolini, Henri Michaux, Gerard de Nerval, César Vallejo, Siamanto, and Adonis (on Defixiones).