She was one of the main figures of the tropicalia music scene in Brazil in the late 1960s and appeared on the acclaimed compilation Tropicália: ou Panis et Circencis (1968).

[4][5] Her mother, Mariah Costa Penna, separated from her father, Arnaldo Burgos, after discovering he had a second family in another city.

[6] At the age of 10, Gal befriended sisters Sandra and Andréia Gadelha, the future spouses of singer-songwriters Gilberto Gil and Caetano Veloso, respectively.

[6] While early in her career she performed as Maria da Costa, producer Guilherme Araújo claimed she needed a stage name.

[10] Gal debuted her professional career on the night of 22 August 1964 at the concert Nós, por exemplo (We, For Example), where she performed alongside Veloso, Gil, Maria Bethânia and Tom Zé, among others.

She then left Salvador to live in the house of her cousin Nívea in Rio de Janeiro, following in the footsteps of Bethânia, whose concert Opinião (Opinion) had become a huge hit there.

The following year Gal met Gilberto personally and participated in TV Rio's 1st International Music Festival performing "Minha Senhora", written by Gil and Torquato Neto.

[11] The same year, she participated in the 3rd International Music Festival, performing "Gabriela Mais Bela", written by Roberto and Erasmo Carlos.

In November, she participated in Rede Record's 4th Music Festival, performing the song "Divino Maravilhoso", by Gil and Veloso.

When Gilberto Gil and Caetano Veloso were living in exile in London, she would visit them and keep performing their music, but stayed in Brazil.

[7][13] Gal has recorded songs composed by a number of Brazil's most popular songwriters such as Tom Jobim, Ben and Erasmo Carlos.

[11] Multiple Brazilian celebrities paid tribute to her following her death including then President-elect Lula da Silva, Maria Bethânia, Caetano Veloso, and Gilberto Gil.