The former EastEnders star - who has played senior consultant and former heart surgeon Nick Jordan since 2008 - will appear in four final episodes that are due to commence tomorrow (Saturday, January 12).
"#NickJordan is back for four final episodes from this Saturday," the official series Twitter announced this evening. "Prepare for the emotional farewell #GoodbyeNick."
It added: "Sad news, but let's enjoy #NickJordan in his final four episodes and the other medics will be here to get us through this difficult time."
Casualty recently released a special online webisode to introduce four new characters. Twitter accounts for each of the trainee nurses were also set up, allowing fans of the show to follow and get to know the foursome before they made their debut on the TV show last weekend (January 5).
Casualty continues tomorrow at 8.50pm on BBC One.