Haydn Gwynne started acting in her mid-twenties with her first prominent television role as feminist lecturer Dr Robyn Penrose in the BBC dramatisation of David Lodge's Nice Work in 1989.
This was followed by a comedy role in Drop the Dead Donkey in 1990. She later became a regular in Peak Practice and went on to star in Merseybeat in 2001. Her television appearances are now in one off dramas or short series including as the role of Julius Caesar's wife Calpurnia, in the TV series Rome, the first Christmas special of Midsomer Murders and Lewis.
Her theatre credits numerous productions with the Royal Shakespeare Company, Hedda Gabler at the Bolton Octagon, Ziegfeld and as Mrs Wilkinson in Billy Elliot the Musical at the Victoria Palace Theatre for which she was nominated for an Olivier Award. She reprised this role on Broadway and won the Outer Critics Circle Award, Theatre World Award, and Drama Desk Award as well as being nominated for a 2009 Tony Award.