Borenstein's career began with her debut Tricycle in 1970. She began free-lancing at the National Film Board of Canada in 1976 when she created Traveller's Palm, a visualization of the poem by P.K. Page, done in bas-relief clay animation. In 1980, Borenstein became a member of the publication board of the International Animated Film Association (ASIFA) in Canada, a newsletter focusing mainly on the activity of Canadian members of the association.[7] Borenstein's work has been showcased by Quickdraw Animation Studios[8] and at the Genie Awards, the Columbus International Film & Video Festival, and the Festival of Films on Art in Lausanne, Switzerland.[3] She is the company officer of Illumination Animation Inc., an animation company based in Montreal and active since 1994[9] that has produced several of her films including Mother's Colours (2011),One Divided by Two: Kids and Divorce (1997) and Lida Moser Photographer (2018).[citation needed] From 1984 to 2008, Borenstein was a part-time professor in film animation at Concordia University.[3]
Borenstein's best known work is the biographical documentary The Colours of My Father: A Portrait of Sam Borenstein, released in 1992. Produced by the National Film Board and Imageries Inc., the film details the life and career of her father Sam Borenstein. It includes interviews with her mother, Judith; archival material; and a combination of Borenstein's original animation, reproductions of her father's work, and time-lapse sequences taking place in Montreal and the Laurentian Mountains.[10]