Her career path to becoming a singer was unconventional – formerly a professional violist, Lieberson did not shift her full-time focus to singing until she was in her thirties.

Her professional career as a singer began in 1984, and in 1985 she made her operatic debut after meeting Peter Sellars, appearing in his 1985 production of Handel's Giulio Cesare.

She began her career as a soprano, singing roles such as Handel's Theodora and Donna Elvira in Sellars' notorious production of Don Giovanni, but soon gravitated to the mezzo-soprano range.

Among the roles she sang during her career are Sesto (Mozart's La clemenza di Tito), Carmen (Bizet's opera of the same name), Beatrice (Berlioz's Beatrice et Benedict), Mélisande in Pelléas et Mélisande (concert performances under Bernard Haitink), Médée (title role of Charpentier's Médée, with William Christie and Les Arts Florissants), Phèdre (Jean-Philippe Rameau's Hippolyte et Aricie), Theodora and Irene (Handel's Theodora; Theodora at Göttingen with Nicholas McGegan, Irene at Glyndebourne with Christie), Minerva (Monteverdi's Il ritorno d'Ulisse in patria with René Jacobs), Ottavia (Monteverdi's L'incoronazione di Poppea with Marc Minkowski) and the title roles of Handel's Ariodante and Serse.

Canadian vocal coach Denise Massé said in a New Yorker magazine interview, Lorraine is like Callas in her determination to dig as deeply as possible into the character — to find all the grain in the wood.In June 2005, Hunt Lieberson made her last appearance in Amsterdam, performing the Sellars staging of Bach's Ich habe genug.

In the late 1980s and early 1990s, before her marriage to Peter Lieberson, Lorraine Hunt rose to prominence in the repertoire of George Frideric Handel.

Her recordings include Ariodante, Serse, Messiah (as a soprano), Clori, Tirsi e Fileno, Theodora, Susanna, and two CDs of Handel arias.

Hunt Lieberson's 1999 debut at Wigmore Hall, a performance of lieder by Schumann (Frauen-Liebe und Leben, Op.