[11] Other theatrical credits include Sunset Boulevard, Les Misérables, The Journey Girl, and as Liza Minnelli in The Boy from Oz with Todd McKenney.

She was an Original London Cast member of the Queen and Ben Elton musical We Will Rock You, starring Tony Vincent and Hannah Jane Fox which opened at the Dominion Theatre on 14 May 2002.

She returned to Australia in 2003 for the Australian Tour, which ran from 7 August 2003 – 13 March 2005[15] in the role of Oz – short for Ozzy Osbourne (formerly Meatloaf in London) The production also starred Michael Falzon as Galileo, Kate Maree Hoolihan as Scaramouche, and Jason Chong– (later Daniel Fletcher) as Brit.

She starred alongside Todd McKenney (Lord Evelyn Oakleigh), Wayne Scott Kermond (Moonface Martin), Christie Whelan (Erma) and Alex Rathgeber (Billy Crocker).

Harrison originated the role of Paula Pokrifki in the World Premiere of An Officer and a Gentleman[20] at the Sydney Lyric Theatre which ran for six weeks in 2012.

Harrison was cast opposite Ben Mingay as Zack May, in a production that included Alex Rathgeber, Kate Kendall, Bert Labonte, Bartholomew John and Tara Morice.

Harrison stepped in to sing the role of Anita in The Production Company's 2015 West Side Story, when actor Deone Zanotto suddenly came down with laryngitis.

"[14]With Wicked castmate Lucy Durack, she sang the Australian national anthem Advance Australia Fair at the opening of the AFL Grand Final.

[36] Harrison performed the song "One Short Day" with fellow Wicked cast members at the 2008 Melbourne Myer Windows display to kick off the Christmas Parade.

On 24 December, Harrison and Durack sang at Vision Australia's Annual Carols by Candlelight Concert at the Sydney Meyer Music Bowl.

[50] Harrison joined Michael Ball, Lea Salonga, David Harris and Marie Zamora for Enda Markey Presents Do You Hear The People Sing at Shanghai Grand Theatre from 27 November until 1 December 2013.

[52] Do You Hear The People Sing features the work of Alain Boublil and Claude-Michel Schönberg including music from Les Misérables and Miss Saigon.