[2] He made his professional stage debut at the Ludlow Festival in 1956, playing Gaveston in Marlowe's Edward II.

His major roles on stage include Newman Noggs in Nicholas Nickleby; Charlie Marsden in Strange Interlude; Gaev in The Cherry Orchard; the Cardinal in The Duchess of Malfi; Alceste in The Misanthrope; Frank Ford in The Merry Wives of Windsor; Malvolio in Twelfth Night, King Cymbeline in Cymbeline; Dr Dorn in The Seagull; Sir Anthony Blunt in Single Spies; the title role in 'Cyrano de Bergerac'; Krapp in Samuel Beckett's Krapp's Last Tape; Donner in Tom Stoppard's Artist Descending a Staircase; and Tiresias in Sophocles' Antigone.

On television, he has made appearances in Journey's End, Man at the Top (1972), The Ash Tree (1975), Casting the Runes (1979), Maigret, No Strings, Dead of Night, The Brief, Midsomer Murders (a role he took on after Ian Richardson died a few days before production was to begin), The Land Girls and Doctors.

His film roles include Richard St Ives in Mike Newell's An Awfully Big Adventure (1995), Lord Peter Wimsey, Dr. Pritchard in Gulliver's Travels (1996), Foster in A Christmas Carol (1999), Dom Vladimir in The Statement (2003), and Aesculapius in Pope Joan (2009), directed by Sonke Wortmann.

[7] His book, Slim Chances and Unscheduled Appearances was published in 2011[8] and launched with a sell-out Platform at the National Theatre.

Petherbridge is the author of Pillar Talk (or Backcloth and Ashes), a one-man show about Saint Simeon Stylites, published in 2005.

[9] In 2011, Petherbridge published an autobiographical anthology of essays, poems and artwork under the title Slim Chances and Unscheduled Appearances, which includes a foreword by Sir Ian McKellen.