Hall first came to be known to the public when she joined the second Brasil project of Bossa Nova master Sergio Mendes, Brasil '66. Unlike the previous incarnation, Brasil '66 was an instant success - making a significant impact on the charts with its first single, a version of the Brazilian song "Mas Que Nada". Much of the song's appeal was due to the distinctive, multi-tracked vocals of Hall.

A series of popular interpretations followed, including their take on The Beatles' "Fool on the Hill". Though many associate her with Brasil '66's hit rendition of Burt Bacharach's "The Look of Love" on the album Look Around (which reached #4 on the pop charts in 1968), the lead on that single was actually handled by Mendes' other singer of that period, Janis Hansen.

The band toured alongside A&M labelmates (and label founder) Herb Alpert and the Tijuana Brass in 1966. She left Brasil '66 in 1971 and married Alpert in 1974.

With her husband assuming production and arranging duties, Hall embarked on a solo career, beginning with 1972's Sun Down Lady and following up with Hello It's Me in 1975. A new album would appear nearly every year until 1985's Es Facil Amar, for which Hall would be awarded a Grammy for Best Latin Pop Performance. Her albums maintained their popularity, primarily in the Latin market, but some mainstream presence was kept, particularly with her contribution of the title song to the James Bond film Never Say Never Again in 1983.

After raising a family with Alpert and writing fiction, she returned in 1998 with the album Brasil Nativo on the Windham Hill label.