Gunild Keetman Polyxeni Matey – Roussopoulou Polyxeni Matey – Roussopoulou (1902–1999) was born into an upper-class family. Her father was the chemist Othon Roussopoulos, founder of the first technical vocational school in Greece (Roussopoulos Academy) and a pioneer in the development of conservation techniques for antiquities, including the Antikythera Mechanism and other artifacts from the ancient Antikythera Shipwreck.

She attended a German kindergarten and elementary school, received home tutoring, and completed her education attending the last grade of the first Greek girls' high school. There, she met the demotic Greek language advocate Manolis Triantafyllidis, who played a decisive role in shaping her thinking and her love for the Greek vernacular. They remained friends until the end of his life.

She began piano lessons at the Athens Conservatory at the age of six. After her father's death in 1922, she and her mother moved to Leipzig in 1924, in an environment rich in cultural stimuli, where she continued her piano studies at the Leipzig Music Academy (Conservatorium), from where she received her diploma in 1925.

In 1926, she married the Greek-Romanian painter Georg Alexander Mathey (Georgios Alexandros Matey) and in 1928, they moved to Berlin, where she focused more intensively on piano and began her career as a soloist. In 1929, she performed the world premiere of Nikos Skalkottas' Concerto for Violin and Piano in Berlin.

In 1930, she visited Greece as a guest soloist and, in 1931, settled in Athens. She studied Byzantine music with Simon Karas. Her interest in Greek culture brought her into contact with Angelos and Eva Sikelianos and Angeliki Hatzimichali.

From 1931 to 1935, she worked at the school of her cousin Koula Pratsika, which led her to focus on music and movement education, leaving behind her career as a soloist. In 1935–1936, she studied "German Gymnastics" at the Günther School in Munich, where her acquaintance with Carl Orff marked the beginning of a collaboration and friendship that lasted until the composer’s death in 1982.

From 1931 to 1935, she worked at the school of her cousin Koula Pratsika, which led her to focus on music and movement education, leaving behind her career as a soloist. In 1935–1936, she studied "German Gymnastics" at the Günther School in Munich, where her acquaintance with Carl Orff marked the beginning of a collaboration and friendship that lasted until the composer’s death in 1982.

In 1938, she founded the "Polyxeni Matey Roussopoulou School of Rhythmic Gymnastics," which became a hub for arts and letters and a meeting place for artists of that era.

The war that began in 1940 separated her from her husband and forced her to close the school during the German occupation. In 1949, she visited Salzburg, where she met Gunild Keetman and discussed the children's classes and her other activities at the Mozarteum.

Between 1950 and 1956, the Matey School operated a three-year professional program, with instructors such as Yvonne de Chirico, Georgios Vakalo, Spyros Peristeris, and Olga Kakridi. The students' performances were a great success. The musical compositions of the performances were often composed by Argyris Kounadis. In 1949, a school performance featured students dancing to Nikos Skalkottas’ suite "The Land and the Sea of Greece" and reciting Ilias Venezis’ "Hymn to Dance," works created specifically for the event. The sets were designed by the renowned painter Nikos Hadjikyriakos-Ghikas.

Between 1950 and 1956, the Matey School operated a three-year professional program, with instructors such as Yvonne de Chirico, Georgios Vakalo, Spyros Peristeris, and Olga Kakridi. The students' performances were a great success. The musical compositions of the performances were often composed by Argyris Kounadis. In 1949, a school performance featured students dancing to Nikos Skalkottas’ suite "The Land and the Sea of Greece" and reciting Ilias Venezis’ "Hymn to Dance," works created specifically for the event. The sets were designed by the renowned painter Nikos Hadjikyriakos-Ghikas.

In 1963, she published the first bilingual volume (Greek and German) entitled "Greek Folk Songs and Dances,"featuring 14 traditional songs arranged for an Orff orchestra, suitable, as she herself pointed out in the introduction, for children over ten years old. In 1968, she published the second volume, emphasizing speech as a tool for Orff music and movement education.

In 1961, the year the Orff Institute was founded in Salzburg, Matey was invited to teach there for the first time. In 1962, she accompanied Orff and a group of close collaborators to Canada, where she conducted seminars introducing Schulwerk at the University of Toronto.

Her contribution to the growth of Orff music and movement education in Greece was decisive in the following decades. Apart from the two volumes of Greek Orff-Schulwerk, she also wrote additional books and articles. In 1970, the "Institute of Modern Hellenic Studies – Manolis Triantafyllidis Foundation" at Aristotle University of Thessaloniki published her book "The First Songs," a collection for preschool children.

In 1978, she published the highly significant book "Rhythmics," which was reissued in 1986 and became the first Greek-language book on rhythmics as a pedagogical approach, introducing the term “music and movement education" to Greece.

In 1992, Matey released "Donia Helidonia" (published by Filippos Nakas publications), a collection of music and movement games for preschool children. That same year, she donated her monograph "Rhythm" to E.S.M.A. (Hellenic Orff-Schulwerk Association), which later published it. In 1993, she co-authored the book "RRRRRO" with her collaborator Angelika Slavik, published by Schott Music.

In 1985, Foteini Protopsalti organized a seminar on Orff music and movement education in collaboration with the Panhellenic Association of Music Teachers and the Matey School at Moraitis School. The seminar's great success led to the gradual establishment of a professional course of study in Orff music and movement education at the Moraitis School, where Polyxeni Matey served as an advisor, especially during its early stages, remaining involved until the end of her life.

The Matey Dance School (matey.gr) continues to operate in Marousi, where it relocated in 1993. Its artistic director is Polyxeni Matey's granddaughter, Anna Matey.

The school is also the place where E.S.M.A.’s (Hellenic Orff-Schulwerk Association) base is located.