Born in New York City, she was the daughter of Frances (née Price) and Joseph Shakow. Her father was an outfitter, who provided equipment to polar explorers; her mother was a homemaker. Shakow was a 1948 graduate of Swarthmore College in Pennsylvania and gained bachelor's and master's degrees from the University of Oxford in 1950 (two years rather than three) and 1954 respectively. Tutored by both A.J.P. Taylor and Isaiah Berlin, she asked the former to be her doctoral supervisor, but Taylor disapproved of the PhD which he did not consider worthwhile. She received her doctorate in History from Harvard in 1957.
Steiner specialised in foreign relations, international relations, 20th century history of Europe and of the United States. Richard J. Evans has described her two volumes in the Oxford History of Modern Europe (The Lights That Failed and The Triumph of the Dark) as the "standard works" on international diplomacy between the two world wars.
From 1968 to 1995, Steiner was a Fellow of New Hall (now Murray Edwards College) of the Cambridge University. In 2007, she was elected a Fellow of the British Academy (FBA), the UK's national academy for the humanities and the social sciences.
- Steiner, Zara S. (1969). The Foreign Office and foreign policy, 1898-1914. Cambridge: University press. ISBN 978-0521076548.
- Steiner, Zara S.; Neilson, Keith (2003). Britain and the origins of the First World War (2nd ed.). Basingstoke: Palgrave Macmillan. ISBN 978-0333734667.
- Steiner, Zara (2005). The lights that failed: European international history 1919–1933. Oxford: Oxford University Press. ISBN 978-0198221142.
- Steiner, Zara (2010). The triumph of the dark: European international history 1933–1939. Oxford: Oxford University Press. ISBN 978-0199212002.
- Ordine, Nuccio (14 February 2020). "È morta Zara Shakow, moglie di George Steiner". Corriere della Sera (in Italian). Retrieved 14 February 2020.
- Schudel, Matt (16 February 2020). "Zara Steiner, distinguished scholar of diplomatic history, dies at 91". The Washington Post. Retrieved 16 February 2020.
- Evans, Richard J. "Zara Steiiner obituary". The Guardian. Retrieved 24 February 2020.)
- "Steiner, Dr Zara Shakow (1928–)". history.ac.uk. Institute of Historical Research. Retrieved 30 October 2016.
- "Steiner, Dr Zara". Who's Who 2016. Oxford University Press. November 2015. Retrieved 30 October 2016.
- "Dr Zara Steiner". britac.ac.uk. The British Academy. Retrieved 29 October 2016.