The actress, who played Tina Carter in the BBC One soap, will star in the one-night ITV musical extravaganza, which is to be filmed and air later this month.
Luisa will appear in the 2021 show alongside Shaun of the Dead's Jessica Hynes, news broadcaster Robert Peston and actor Barney Walsh.
Former Strictly Come Dancing stars Judge Rinder and Dr Ranj Singh round out the cast.
Hosted by John Barrowman, All Star Musicals will see this year's six celebrities belt out a range of musical numbers from shows including Chicago, Guys & Dolls and The Greatest Showman.
Each celeb will receiving mentoring from theatre legend Elaine Paige, expert choreographers and vocal coaches, as they perform in front of a West End chorus line.
Alongside Elaine on the judging panel will be Trevor Dion Nicholas and Les Misérables star Samantha Barks, with the panel and Barrowman joining forces to open the show with a special performance of Hairspray hit 'You Can't Stop The Beat'.
The announcement follows Luisa previously denying she will return to EastEnders as Tina Carter, while teasing a forthcoming TV project (presumably All Star Musicals).
"I LOVE musicals!" Luisa said. "I love singing. This is a secret dream to do a show like this!
"It scares me hugely but I really wanted to teach my kids that even though something may be so out of your comfort zone, do it anyway – it could be the best memory of your life. And life is all about pushing boundaries and making memories, right?"
All Star Musicals debuted in 2019 and was won by Coronation Street star Daniel Brocklebank.
All Star Musicals will return to ITV later this month.
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