Tunzelmann was educated in Brighton and at University College, Oxford University. There she read history and edited both Cherwell and Isis. She has worked primarily as a researcher and lives in London.

She has contributed to The Political Animal by Jeremy Paxman, The Truth About Markets by John Kay, Does Education Matter? by Alison Wolf, and Not on the Label by Felicity Lawrence. She has been recognized as a Financial Times Young Business Writer of the Year. Most recently she has collaborated with Jeremy Paxman on his book, On Royalty.

The Secret History of the End of an Empire (2007) is her first book, detailing the liberation of India from the British Empire.

Recently, she has begun writing a weekly column for The Guardian entitled "Reel history", in which she discusses and rates popular films for their historical accuracy.