Lieven was educated at Downside School, a Benedictine Roman Catholic boarding independent school in Stratton-on-the-Fosse, near Shepton Mallet in Somerset, followed by Christ's College, Cambridge, where he graduated top of the class of 1973 (Double First with Distinction), and was a Kennedy Scholar at Harvard University in 1973/4.

Lieven is a writer on Russian history, on empires and emperors, on the Napoleonic era and the First World War, and on European aristocracy.

He was elected in 2001 Fellow of the British Academy, and was head of the History Department at the London School of Economics from 2009 to 2011; he was appointed lecturer there in 1978, and professor in 1993.

[5][6] In May 2016, Lieven was one of 300 historians who were signatories to a letter to The Guardian warning voters that if they chose to leave the European Union in a process called Brexit on 23 June of that year, they would be condemning Britain to irrelevance.

[8] Lieven said:[9] You couldn't completely rule out the strangest sexual antics in young aristocratic St Petersburg, though brother-sister incest is perhaps a bit ripe....