She was nominated for an Olivier award as Best Supporting Actress for her performance as Olivia in the RSC's Twelfth Night, directed by Greg Doran, which played at the Duke of York's Theatre in the West End in 2010.
Other television credits include episodes of Absolute Power, Midsomer Murders, The Commander, Casualty and Trial & Retribution.
At the Bush Theatre in London, she premiered Oscar winner Rebecca Lenkiewicz’s play, The Invisible, directed by Michael Oakley.
In 2015 Gilbreath filmed the Justin Chadwick-directed Tulip Fever, with Alicia Vikander and Christoph Waltz, and appeared as Georgina Francis in the BBC TV series Father Brown episode "The Time Machine".
She also performed in the World Premiere of Florian Zeller's The Lie, directed by Lindsay Posner, and appeared at the Hampstead Theatre in the black comedy Mother Christmas.