He wrote the original play Riflemind (2007), which premiered at the Sydney Theatre Company to favourable reviews, with Hugo Weaving starring and Philip Seymour Hoffman directing the London production.

[1][2] As a playwright, Upton created adaptations of Hedda Gabler, The Cherry Orchard, Cyrano de Bergerac, Don Juan (with Marion Potts), Uncle Vanya, The Maids, Children of the Sun[3][4] and Platonov for the Sydney Theatre Company (STC) and Maxim Gorky's The Philistines for the Royal National Theatre in London.

[5] Upton's original play Riflemind opened with Hugo Weaving, playing an ageing rock star planning a comeback, at the Sydney Theatre Company on 5 October 2007, and received a favourable review in Variety.

[11][12][13][14][15][16] In 2008, Upton and wife Cate Blanchett became joint artistic directors of the Sydney Theatre Company for what became a five-year term.

[26][22] In June, 2014, Upton was recognised with the Rotary Professional Excellence Award, an award instituted "to honour a person who has demonstrated consistent professional excellence in his or her chosen vocation by contributing to the benefit of the wider community beyond their typical workplace role".