Edmundson's first play Flying was produced at the National Theatre Studio in 1990. Since then, her work for the theatre has included: The Clearing, first performed at the Bush Theatre; Mother Teresa is Dead, at the Royal Court Theatre; and four stage adaptations for Shared Experience Theatre - Anna Karenina and The Mill on the Floss, both of which toured nationally and internationally, War and Peace, which was produced at the National Theatre in 1996, and Gone to Earth which was seen on tour and at the Lyric Hammersmith.
Her adaptation of Jamila Gavin's award-winning children's novel Coram Boy premiered at the National in November 2005 and came back for a revival at the same venue a year later. Her most recent work for Shared Experience, Orestes - Blood and Light, toured in the UK in autumn 2006 and played at the Tricycle Theatre until December 2006. The Clearing received the John Whiting Award for best new play, as well as a Time Out Award. She also won TMA and Time Out Awards for The Mill on the Floss, Anna Karenina and most recently, a Time Out Award for Coram Boy. Edmundson has written two short films for television: One Day for BBC2 and Stella for Channel 4, and her adaptation of The Voyage Out was heard on BBC Radio 4 in 2006. She took part in the Bush Theatre's 2011 project Sixty Six for which she wrote a piece based upon a chapter of the King James Bible In 2012, her play about Sor Juana Inés de la Cruz, The Heresy of Love, was produced by the Royal Shakespeare Company at the Swan Theatre, Stratford-Upon-Avon, directed by Nancy Meckler. 
- "Coram Boy". The Guardian. 16 November 2005. Retrieved 6 May 2011.
- Helen Edmundson at the Internet Movie Database
- An interview with Helen Edmundson, author of Mary Shelley