Her character will take on the role of the previous director, Steve Savage, played by comedian Jason Manford, who was taken away by the police at the end of series 14 for helping to cover up Boz Osborne’s murder.
Coulson, 64, said: “I am delighted to be joining Waterloo Road as the new headteacher, Mrs Stella Drake.
“It’s a role I haven’t played before, so I’m really enjoying peeling back the layers of who Stella is and seeing how the teachers and students react to her no-nonsense approach.
“Waterloo Road deals head-on with social issues that are so important to watch on television, and this series will be no different.”
Dame Stella joined the school as the students “became increasingly unruly after the last term”, according to producers, and she “soon felt out of date as she encountered the school’s modern pastoral approach”.
In a first-look clip, she tells teachers, “I know you’re probably still feeling battered and hurt after recent events, but we need to take a good, honest look at what changes are needed to turn this school around.”
The TV show, which explored the lives of pupils at a state school in Greater Manchester, originally ran on the BBC between 2006 and 2015 before returning in 2023.
Coulson is best known for her role as Carol Jackson in the British soap opera EastEnders, in which she last appeared in 2015.
Cameron Roach, executive producer of Waterloo Road, said: “We’re really excited to have Lindsey Coulson join Waterloo Road, she’s completely embraced the spirit and spirit of the show and she’s completely taken the role of Dame Stella Drake, we can’t wait for the audience to meet her.
“That the show has landed an actor of Lindsay’s caliber is a testament to the continued ambition and dedication of our writing and story teams, as well as our brilliant cast and crew.”
Lindsay Salt, Director of BBC Drama, added: “It’s a real honor to have an actor of Lindsay Coulson’s caliber take over the reins of Waterloo Road. Dame Stella Drake is a force to be reckoned with and we know fans of all ages will love watching her.”
Waterloo Road returns to BBC iPlayer and BBC One in 2025.