Bevan was born in Hertford in southeast England in 1985 into a musical family: her siblings Sophie Bevan and Benjamin Bevan are both successful vocal soloists, and their father, David Bevan, was a conductor. Mary attended Trinity College, Cambridge, studying Anglo-Saxon, Norse, and Celtic literature. She took singing courses at Cambridge and then, in a common pattern, went on to the Royal Academy of Music, where she studied with Lillian Watson and Audrey Hyland. Bevan has appeared at Covent Garden, the English National Opera, and the Opera de Monte Carlo, among others. She is a winner of the Royal Philharmonic Society's Young Artist Award. Her roles have included Arpago in Vivaldi’s L'Incoronazione di Dario for England's Garsington Opera; Pamina and Papagena in Mozart’s The Magic Flute at the Palestinian Mozart Festival and British Youth Opera, respectively; and Rebecca in the world premiere of Nico Muhly's Two Boys in 2011. Unusually among top-flight operatic sopranos, she has appeared as Yum-Yum in Gilbert & Sullivan's The Mikado. Bevan is also in demand as a soloist in concert music, having appeared with such groups as the Orchestra of the Age of Enlightenment and the English Concert, with which she toured Asia.
Bevan has recorded for the Signum Classics, Delphian, and Champs Hill labels, among others. She made her recording debut in 2012 on Stone Records, with an installment in a cycle of songs by Hugo Wolf, and her recording schedule in the late 2010s and early 2020s has been vigorous. In 2020, she was heard on a pair of albums: The Divine Muse, a recital of songs by Haydn, Schubert, and Wolf, and a multi-artist album of songs by Ian Venables, Love Lives Beyond the Tomb. ~ James Manheim, Rovi