Rossana Casale was born in New York City on July 21, 1959, the daughter of the Italian-American photographer Giac Casale and an Italian mother. Soon after her birth the family moved to Venice and then to Milan, where she grew up. She enrolled at the Giuseppe Verdi Conservatory in Milan to study singing and percussion, and began her career in the late 1970s as a backing vocalist with a band called Albero Motore. Through the early 1980s she was also a studio voice on Italian dance-music productions for Klein & M.B.O., Kano, Mike Francis and Pink Project, including the Klein & M.B.O. single "Dirty Talk" (1982), which became an underground hit outside Italy.

Her own career as a pop singer started with "Didin" (1983), co-written with Alberto Fortis, and a self-titled debut album in 1984 produced by members of Premiata Forneria Marconi. She entered the Sanremo Festival with "Brividi" in 1986 and "Destino" in 1987, and won the television contest Premiatissima 86 with "Nuova vita." Around the time of her second album, La via dei misteri, she was invited to perform at the Umbria Jazz Festival in Perugia, and Italian Wikipedia says her records then moved toward more sophisticated jazz sounds, which brought her first recognition at Umbria Jazz.

Incoerente Jazz (Philips, released March 29, 1989) was the first of her records to carry the word in its title. Maurizio Fabrizio arranged it and played piano, with Andy Pask on bass, Charlie Morgan on drums, Clem Clempson on guitar and a string orchestra, and with two Milan jazz players in the credits: tenor saxophonist Gianni Bedori on two tracks, and Bruno De Filippi on guitar and harmonica on another, alongside bassist Luciano Milanese. Its single "A che servono gli dei" took her to Sanremo for a third time. Lo stato naturale (1991) followed with "Terra," a Sanremo entry that mixed ethnic and jazz colors, and in 1993 she finished third at Sanremo in a duet with Grazia Di Michele, "Gli amori diversi."

Jazz in Me (CGD, 1994) was her first album given over entirely to jazz. It collects eleven standards, among them "Every Time We Say Good-Bye," "Don't Explain," "Summertime" and Thelonious Monk's "Blue Monk," and a reviewer who heard it describes a four-day recording made without overdubbing. The core group was pianist Riccardo Zegna, saxophonist Carlo Atti, bassist Luciano Milanese, who produced the record with Casale, and drummer Carlo Milanese, with guitarist Sandro Gibellini on "Don't Explain," pianist Andrea Pozza on "How Long Has This Been Going On," trumpeter Marco Tamburini on "Blue Monk" and cellist Bruno Briscik on two tracks. The theatre opened up for her next: she made her stage debut in an Italian production of An American in Paris (1995) and won the Bob Fosse Prize for best debuting actress, later played Sugar in Some Like It Hot and Audrey in Little Shop of Horrors, and in 2007 wrote and performed her own musical, Otto donne ed un mistero.

Jazz then became a recurring strand rather than a single detour. Jacques Brel in Me (Carisch, 1999) recast Brel's songs with pianist Luigi Bonafede, bassist Luciano Milanese, drummer Enzo Zirilli and reedman Claudio Capurro, and Strani frutti (2000) was made with Bonafede, Zirilli and Carlo Atti. Her record of Billie Holiday songs, Billie Holiday in Me (2004), puts twelve pieces from the repertoire of Billie Holiday, from "You've Changed" and "Lover Man" to "God Bless the Child," on one disc under her own production, and was followed by about 250 concerts across Italy. Drummer Mattia Barbieri says in his own biography that he played in her sextet around 2003 and 2004. Merry Christmas in Jazz (2009) is a fifteen-track Christmas set recorded in September 2009 that she produced and arranged with Bonafede, bassist Aldo Mella, drummer Francesco Sotgiu and saxophonist Roberto Regis.

Alongside the records she became a teacher of the idiom. Italian Wikipedia lists her as a jazz singing instructor at the Cuneo conservatory (2009 to 2011), at Parma (until 2016), at Frosinone (2017) and at Pescara (2018), and says that in 2019 she took a permanent post teaching pop-rock singing at the Arrigo Boito conservatory in Parma. She has been a vocal coach on several editions of the Italian television talent show X Factor and, in 2015, sang "Era d'estate" on Momenti di jazz, a Musica Jazz magazine tribute to Sergio Endrigo. Il signor G e l'amore (2014) honored Giorgio Gaber, and in 2022 she released Trialogo with Grazia Di Michele and Mariella Nava under the name Cantautrici. Joni, a Joni Mitchell tribute recorded in Rome in July and September 2022, was a finalist at the 2023 Premio Tenco in the category for song interpreters, and the same year she received the Premio Giorgio Gaber. Almost Blue (Giotto Music, 2024) returned her to straight jazz with a quintet, and on January 8, 2026 she brought the program to the Bonaventura Music Club in Buccinasco, near Milan.

Casale is a pop singer who built a second, durable career in jazz, and her catalog is organized less by band than by tribute: Jazz in Me is a standards program, Billie Holiday in Me a single-singer homage, Jacques Brel in Me a chanson book rethought for a jazz trio, Joni a songbook of Joni Mitchell, and Almost Blue a concept album built around one color word. She has said that Mitchell's records shaped her from the start and that she learned to play guitar by listening to them. Her pop side, with the Sanremo entries, the television work and the theatre, is a large part of her public career and is the reason she is better known in Italy as a popular singer than as a jazz singer.

What places her in the jazz world is the company she keeps and the work she has repeated. A stable circle of Italian jazz players, among them Luigi Bonafede, Carlo Atti, Luciano Milanese and Enzo Zirilli, appears on record after record from Jazz in Me to Almost Blue, and her years of teaching jazz singing in conservatories mark the idiom as part of her working life rather than an occasional visit. Italian Wikipedia cites Roberto Franchina's 1998 dictionary of Italian jazz, Nuovo jazz italiano, as a reference for her entry.