Official records indicate at least four different birthdates for Mildred Ethel Azcoaga Burton. Her biographical accounts are usually full of confused or incorrect information, often provided by M. Burton herself. She was born in the city of Paraná, in Entre Ríos province. She studied at the Escuela Provincial de Bellas Artes de Entre Ríos, and later at the Escuela Superior de Bellas Artes Ernesto de la Cárcova in Buenos Aires.
Painting was her principal medium, although she worked in others, making murals, objects and illustrations, and doing performances as well. Her work, notable for its technical mastery, incorporated elements from the nineteenth-century Arts & Crafts tradition, the Surrealism movement and Argentine political realism of the 1970s and 1980s, as documented in the 2020 posthumous exhibition Mildred Burton: National Fauna curated by Marcos Krämer at the Museo de Arte Moderno in Buenos Aires. Although the media insisted on classifying her as a Surrealist, in an interview with Alejandra Casal the artist explained that the raw material for her work was not dreams but reality. She also said that she had always liked to write and her paintings arose from stories she had written.

M. Burton joined the Postfiguración group in 1979, along with Elsa Soibelman (born 1941), Diana Dowek (born 1942), Alberto Heredia (1924-2000), Norberto Gómez (1941-2021) and Jorge Álvaro (born 1949). Notable works from those years include the oil painting La hora de las visitas [Visiting hours, 1979] and the black and white photograph with watercolour and pencil additions called Invasión II (1980). During the 1980s she worked with Abuelas y Madres de Plaza de Mayo (mothers and grandmothers of those “disappeared” by the military junta during the 1976-1983 “dirty war”), taking part in exhibitions and actions demanding the truth about what happened to them, justice for those responsible and the restoration of the country’s forcibly supressed memory. She also gave operatic performances together with Federico Klemm where they read ironic speeches and recreated ancient myths, such as Los Tres Rostros del Arte [The three faces of art, 1992]. In 1991 she made the ceramic mural A tres niñas argentinas inmoladas: Jimena Hernández, Nair Mostafá y María Soledad Morales [For three sacrificed Argentine girls: Jimena Hernández, Nair Mostafá et María Soledad Morales] for the Dorrego station of the Buenos Aires underground line B. With this memorial to murdered schoolgirls the artist took a stand against what today is called gender-based violence.

Starting in 1969 she took part in more than four hundred and fifty art shows in Argentina and abroad, and received a great many prizes and honours, among them the Premio Günther del Museo Nacional de Bellas Artes in 1997 and the Premio Konex in 2002. She taught workshops at the Escuela Superior de Bellas Artes Ernesto de la Cárcova and gave private lessons in her Buenos Aires studio.

M. Burton’s activist outlook led her to make artworks addressing social issues linked to violence against women – for instance, the series Los contratiempos de J. Pomme [The misadventures of J. Pomme] – and human rights, especially in opposition to Argentina’s military-civilian-ecclesiastic dictatorship, for example, the series La familia del torturador [The torturer’s family].

She died in 2008, leaving a great many artworks that continue circulating among galleries and museums, including the Museo Nacional de Bellas Artes and the Buenos Aires Museo de Arte Moderno.