Educated at Millfield School in Somerset and at Brasenose College, Oxford, Mawer took a degree in biology and worked as a biology teacher for many years. His first novel, Chimera, was published by Hamish Hamilton in 1989, winning the McKitterick Prize for first novels. Mendel's Dwarf (1997), reached the last ten of the Booker Prize and was a New York Time "Book to Remember" for 1998. The Gospel of Judas, The Fall (winner of the 2003 Boardman Tasker Prize for Mountain Literature) and Swimming to Ithaca followed. In 2009 The Glass Room, his tenth book and eighth novel was shortlisted for the Man Booker Prize. His 2012 book The Girl Who Fell From The Sky and its sequel Tightrope (2015) feature the female Special Operations Executive agent Marian Sutro. Tightrope won the 2016 Walter Scott Prize for historical fiction. In 2018, his eleventh novel, Prague Spring, is published, signalling a return to a Czech setting following both Mendel's Dwarf and The Glass Room.
Mawer is married, has two children and three grandchildren. He has lived in Italy for over thirty years and now splits his time between his home near Rome and a house in England.