She is best known for her film performance portraying the wife of aviator Sir Charles Kingsford Smith in Smithy (1946) and for playing the lead role in Autumn Affair (1958–59), Australia's first television soap opera.

Her beauty meant that her photo often appeared in trade publications and she was particularly popular on radio soaps and at the Minerva Theatre in Sydney.

When the family moved to Sydney she became involved in amateur theatre, appearing in plays, particularly Shakespeare, such as The Merchant of Venice and A Midsummer Night's Dream and becoming renowned for her performances in comedy and drama.

[6] Steinbeck made her film debut in the wartime propaganda short, Eleventh Hour (1942), directed by Ken G. Hall.

[8] ) According to Filmink "Steinbeck might have considered going overseas herself – many female actors did so at the time, like Mary Maguire, Jocelyn Howarth and Shirley Ann Richards...

Filming argued that "The filmmakers would have been better off building the movie around Steinbeck... but then, Australian cinema has traditionally demonstrated a poor understanding of how best to exploit potential stars.

In the words of Filmink "Steinbeck played Julia Parrish, middle aged widowed mother who wrote popular novels and had a busy private life.

"[2] She was in two one-off TV dramas, Reflections in Dark Glasses (1960) and Thunder on Sycamore Street (1961) and had a recurring role in a serial, Stormy Petrel (1960).

[18] Although she retired from acting in 1966, she accompanied her husband to Orange, New South Wales, to become a teacher of the arts, running her own drama school and authoring a book titled On Stage: A Practical Guide To the Actor's Craft.