She portrayed Carol Groves in the television show Hollyoaks (1996–2000) and Donna Henshaw in Two Pints of Lager and a Packet of Crisps (2001–2011).
[citation needed] In January 1996, Casey began playing Carol Groves on the Channel 4 soap opera Hollyoaks, in which she remained for over five years.
In 2001, she joined the cast of Two Pints of Lager and a Packet of Crisps, playing Donna Henshaw alongside her Hollyoaks co-star Will Mellor.
In summer 2007, Casey played Serena Katz in a hit run of the musical Fame at the Shaftesbury Theatre in London.
In March 2012, she played Angela in the revival of Mike Leigh's Abigail's Party at the Menier Chocolate Factory, later transferring to Wyndham's Theatre, London.
On 29 June 2012, it was confirmed that Casey would play the role of Judy Bernly in the first UK tour production of the Broadway musical 9 to 5.