[2] He began his career as an actor, one of his earliest roles being in the Hunter Valley Theatre Company's production of David Williamson's The Perfectionist in April to May 1984.
[9] Since January 2020, Berthold has been artistic director-in-residence at the National Institute of Dramatic Art in Sydney.
[13] As of September 2024[update] he is on the boards of Hothouse Theatre[14] and Australian Plays Transform.
[16] In 2010, Berthold was nominated for a BroadwayWorld UK Award for Best Direction of a Play, for his London West End production Holding the Man.
[17] In 2010, Berthold won a Matilda Award for his "repositioning of La Boite Theatre Company and his direction of Hamlet".