As announced last year, the current series will mark the school’s last term in Rochdale. Producers say a “dramatic and explosive storyline” will see a number of current teachers and pupils set up a new independent school in Scotland ready for the eighth and ninth runs.
The BBC have ordered a further 50 episodes to be screened over two years.
The series is produced by Scottish production company Shed.
Shed and the BBC have announced that Brett will join the show when filming for the eighth series starts next month.
The Hamilton-born actress will play Christine Mulgrew who joins the English department as one of the new teachers appointed by headmaster Michael Byrne (Alec Newman) when he sets up the new school.
Brett said she was “thrilled to be joining Waterloo Road.”
“The character I will be playing is such a complex woman, with many issues, and it will be a real departure from what people are used to seeing me do. Not least because for the first time in my career I will be working in my native accent which I am really excited about.”
Cameron Roach, Head of Drama for Shed Productions & Executive Producer, Waterloo Road, says: “We’re delighted to welcome Laurie to Waterloo Road fresh from her success with EastEnders. Making her mark as Christine, a new recruit for Michael Byrne, Laurie’s character is an exciting addition to our brilliant ensemble and will ensure that Waterloo Road makes some noise as it lands on Scottish turf.”