Pyper's theatre credits include "Don Juan in Soho" at the Donmar Warehouse and "Blackwater Angel" at the Finborough Theatre. In 2009 she played Cressida in the first full-scale Shakespeare's Globe production of "Troilus and Cressida". In 2010 she played Lily Cahill in the revival of "Punk Rock". She played Laurel in Douglas Hodge's production of Torch Song Trilogy at the Menier Chocolate Factory in 2012, Mrs Manningham in Gas Light at Salisbury Playhouse in 2014 and Beatrice in A View from the Bridge at York Theatre Royal and Royal & Derngate in 2019.