Between 1955 and 58, she studied painting at the Academy of Fine Arts in Kraków under Profs. Jan Świderski and Emil Krcha. In 1957, she began collaborating with the Cricot 2 Theatre; she participated in all of Tadeusz Kantor's performances and happenings. In 1959, she went on an artistic trip to Paris, where, in 1961, she got married to Kantor. She has been a member of the Grupa Krakowska (Kraków Group) Artistic Association since 1956 – she has taken part in all of its collective demonstrations. In 1962, she began writing her 'endless novel', which was published in 2002 by the Łódź-based Gallery 86, under the title Grandpa’s Diary (Pamiętnik Dziadka).
In 1983-1985, the House of Kantors in Hucisko (between Kraków and Wieliczka) was founded; after Kantor’s death in 1990, it was turned into a museum devoted to the legacy of both artists. In 1994 Maria Stangret-Kantor opened the Tadeusz Kantor Foundation. She cooperated with the Krzysztofory Gallery and Starmach Gallery (both based in Kraków) and with the Foksal Gallery in Warsaw.
She starred in many theatre acts realized by the Cricot 2 Theatre and Tadeusz Kantor: The Well, or the Depth of Thought (Studnia czyli głębia myśli – pantomime, 1956), In a Little Manor House (W małym dworku, 1961), The Madman and the Nun (Wariat i zakonnica, 1963), The Water Hen (Kurka wodna, 1967), The Shoemakers (Szewcy, 1972), Dandies and Frumps (Nadobnisie i koczkodany, 1972), The Dead Class (Umarła klasa, 1975), Where Are the Snows of Yesteryear (Gdzie są niegdysiejsze śniegi, 1978), Wielopole, Wielopole (1980), Let the Artists Die (Niech sczezną artyści, 1985). She also took part in all happenings by Tadeusz Kantor: Cricotage (1965), The Dividing Line (Linia podziału, 1966), La Grand Emballage (1966), The Letter (List, 1967), Panoramic Sea Happening (Panoramiczny happening morski, 1968), A Conversation with a Rhinoceros (Rozmowa z Nosorożcem, 1968), Hommage à Maria Jarema (1968), and An Anatomy Lesson after Rembrandt (Lekcja anatomii według Rembrandta, 1968, 1969, 1971).
Her works are included in the collections of the Art Museum in Łódź, National Museum in Kraków, National Museum in Wrocław, Foksal Gallery, and the Guggenheim Museum in New York, as well as various private collections in Poland and abroad.
In the ‘50s and ‘60s, while she was still studying at the Kraków Academy, Maria Stangret created paintings in the art informel style, which she used to call gestural paintings. She was introduced to the international avant-garde trends by Tadeusz Kantor, who returned from Paris in 1955, where he had been exposed to contemporary abstract art. In the late ‘50s and early ‘60s, Stangret also went on an artistic expedition to France, where she encountered works by such artists as Dubuffet, Wols and Mathieu. Her first art show took place in 1963 at the Brinken Gallery in Stockholm. In 1965, she went abroad once again – this time to the United States (California and New York), where she became interested in Jackson Pollock’s action paintings, as well as the art of Dine, Segal, Oldenburg, and Rauschenberg.
Maria Stangret’s works from that period are characterized by their spontaneity and lightness of brush strokes, combined with a masterful handling of matter. Every now and then, the artist introduced collage into them, also in a way that escaped the two-dimensional surface of a painting – this tendency intensified later on in her practice.
Maria Stangret departed from the informel style in the mid-60s, with the painting series titled Continental Landscapes (Pejzażę kontynentalne). She simultaneously participated in the activities of the Cricot 2 Theatre, founded by Tadeusz Kantor and Maria Jarema. Moreover, she took part in small theatre plays which Kantor directed for Karbunkuł – the theatre of atrocities, run by Andrzej Bursa and Jan Guntner, and played the role of the Vaulter in Kazimierz Mikulski’s Circus, also directed by Kantor.
In 1962, she began writing her 'endless novel' – a literary piece with a collage-like structure, based on excerpts from old handbooks, fiction stories, and her own reports of unimportant, banal situations, all of which were pieced together in an automatic manner. She occasionally published fragments of those texts in her exhibition catalogues (e.g. Krzysztofory in 1965 or Foksal in 1967), however, the complete piece wasn’t published until 2002, under the title Grandpa's Diary (Pamiętnik Dziadka).
In the late ‘60s and during the ‘70s, Stangret began to paint in a minimalist style, relying on plain shapes and geometrical forms. She also introduced three-dimensional elements into her works, i.e. actual objects. This escape from 2D and the typical painting conventions resulted from her methods of combining painting with assemblage. In 1969, Maria Stangret produced a specific amalgamation of painting and nature – by painting over the trunks and branches of the trees in front of the Foksal Gallery with green paint, she created a 'real landscape painting'. She soon started creating conceptual compositions – paintings that were supplemented by objects connected directly to them. Her piece Sky with a Drainpipe (Niebo z rynną, 1970) was made out of a piece of canvas with the sky painted on it and a real drainpipe filled with grey or blue water (depending on the version), stuck under the fabric. Paintings representing chess boards (Chess I and Chess II / Szachy I, Szachy II) were paired with enlarged chess pieces, while others, with blackboards painted on them, were accompanied by boxes of white chalk (Blackboards/Tablice, 1974). Hopscotch (Gra w klasy, 1970) had an outline of the popular children’s game painted on a white background of the painting, which consisted of several elements and spread to the floor surface in a way that encouraged interaction. In these works, the artist was effacing the difference between the actual and representational status of an image of reality. At that time, she also started introducing the motif of a sheet of lined paper with red margin (Sheet from a Notebook / Kartka z zeszytu, 1970), which she elaborated in her future works.