Sosa was born in Tucumán of French and Quechua ancestry. In 1950, at age fifteen, she won a singing competition organized by a local radio station and was given a contract to perform for two months.
Sosa and her late husband Manuel Oscar Matus emerged in the mid-60s in the midst of the nueva canción movement. Her first record was Canciones con fundamento, a collection of Argentinian folk songs.
In 1967, Sosa toured with great success the United States and Europe. In subsequent years, she performed and recorded extensively, broadening her repertoire to include material from throughout Latin America.
After the military junta of Jorge Videla came to power, the atmosphere in Argentina grew increasingly oppressive. At a concert in La Plata in 1979, Sosa was searched and arrested on stage, and the public which came to see her arrested. Prohibited from singing, she moved that year to Paris and then to Madrid the following year.
Sosa returned to Argentina in 1982, several months before the Videla regime collapsed as a result of theFalklands War, and recorded a much-admired live album at the Colón Theater in Buenos Aires, which was laden by political under-currents. Sosa spoke for many with her songs that reflected a yearning for a return of peace and democracy.
In the years following, Sosa relocated to Argentina but continued to tour, performing in such venues as Lincoln Center, Carnegie Hall and the Mogador in París.
Sosa's repertoire continued to broaden, and she made recordings in various styles. She also collaborated frequently with and gave great stimulus to other Argentinian musicians, including León Gieco, Charly García, Antonio Tarragó Ros, Rodolfo Mederos and Ariel Ramírez.
Sosa continues to perform and record. In 2002, she released a double album of live recordings.