Ellison and Gates will take over the roles of Paulette and Warner. They join Faye Brooks, who continues to star as Elle Woods, and Iwan Lewis, who plays Emmett.
Ellison is best known for her role on the television soap opera Brookside. Her stage credits include Chicago and Boeing Boeing. On screen, she played Meg Giry in the film adaptation of The Phantom of the Opera.
Gates was voted runner-up in the first season of the television series Pop Idol, and has starred on stage in Joseph and the Amazing Technicolor Dreamcoat and the 25th Anniversary tour of Les Miserables.
Legally Blonde the Musical, based on the film of the same name, features a score by Laurence O'Keefe and Nell Benjamin, with a book by Heather Hach. The production is directed and choreographed by Jerry Mitchell.