Ellis made her first professional stage appearance in 1998 and went on to make her West End debut in the 2001 revival of My Fair Lady as an understudy for the role of Eliza Doolittle.

"[8][11] Although she had not discovered her vocal ability until she was at college and had started working, Ellis cites her early influences as Liza Minnelli, Elaine Paige and Barbra Streisand; their music she would sing in her bedroom much to the disturbance of her older brother Andrew, now a keen fisherman.

"[14] Whilst attending Stowmarket High School, she completed work experience with Starmakers, a company of holiday entertainers, at Potters Leisure Resort in Hopton-on-Sea.

[18] By the time she graduated in 1998, Ellis had appeared in a number of professional pantomimes for E&B productions including Dick Whittington (1995) and Aladdin (1996) across theatres in the UK as well as performing the title role in Cinderella (1997) at the Cliffs Pavilion in Southend-on-Sea.

[20] By late 2000, she had settled in her first property, a two-bedroom Brockley maisonette, and joined the original cast of Cameron Mackintosh's London revival of My Fair Lady, appointed swing and second of two understudies to Martine McCutcheon in the role of Eliza Doolittle after being scouted by agent Jonathan Greatorex.

[23] Due to the illnesses of both McCutcheon and first understudy Alexandra Jay during the production's run at both theatres, Ellis starred as Eliza Doolittle opposite Jonathan Pryce and Dennis Waterman; her West End debut saw her taking on the lead role with only three hours preparation.

She also played Eva Cassidy in a 2004 workshop production of Way Beyond Blue, a Trevor Nunn-directed and Imogen Stubbs-written piece, in addition to being cast as Ellen in a UK tour of Miss Saigon.

Ellis had been contracted to serve as a temporary standby to Idina Menzel, the original Elphaba, for three months from first performances in September 2006, before taking over to play the lead role full time in January 2007.

[20] Ellis also made numerous appearances at concerts and events, singing songs from the musical, including West End Live in Leicester Square, Walk for Life in Hyde Park, Kids Week in Covent Garden, and the annual Gay Pride Festival in Trafalgar Square, in addition to making an appearance on lunchtime television chat show Loose Women.

[39][40] Playing alongside Kendra Kassebaum as Glinda and Aaron Tveit as Fiyero for her five-month run, Ellis won the Broadway.com Audience Award for Favorite Female Breakthrough Performance in 2009.

[42][43] Produced by Brian May and Steve Sidwell, the EP comprises three tracks: new orchestrations of "Defying Gravity" and "I'm Not that Girl" from Wicked and Queen song "No-One but You (Only the Good Die Young)" that she and May recorded six years earlier.

[47] Upon departure, Ellis had been billed as lead for a total of 116 weeks (omitting absence) in both the London and Broadway companies, making her the longest-serving British actress in the role of Elphaba (until Rachel Tucker later succeeded this feat in June 2012).

[48] Ellis cited the role of Elphaba as the "most challenging [that she had] ever undertaken" stating that it was "a massive journey" to go on at every performance and admits that Wicked "changed [her] life" in terms of boosting her recognition within the entertainment industry.

[49] Whilst still involved in Wicked, Ellis also performed alongside Idina Menzel, Adam Pascal, Josh Groban, Clarke Peters, Marti Pellow and David Bedella in a two-day limited engagement of Chess in Concert at the Royal Albert Hall on 12 and 13 May 2008.

She played the role of Svetlana and upon reflection, stated that to star at the Royal Albert Hall, work with an "amazing" company and sing alongside those particular cast members "was a dream come true."

Following her departure from Wicked, she recorded material with Brian May for her debut album and performed at various live events including her first set of solo musical showcase concerts entitled Kerry Ellis Sings the Great British Songbook at the Shaw Theatre on Euston Road in London.

"[45] The showcase paid tribute to some of Ellis' favourite British composers and lyricists including Take That, Duffy, Andrew Lloyd Webber and Paul McCartney.

[56] Ironically, Ellis had appeared in the BBC talent show I'd Do Anything (2009), mentoring potential Nancys (including Jodie Prenger) in the fore-running to the opening of this London revival.

[58] Ellis first played Nancy on 29 March 2010 to positive reviews, starring alongside Griff Rhys Jones (and later Russ Abbot) as Fagin and Steven Hartley as Bill Sikes.

The album, which was produced by Brian May and recorded at Abbey Road Studios with a 70-piece orchestra, was described by Ellis as one that "tap[s] into all the different areas that [she has] been part of" in her career between the years 2000 and 2010.

May stated that "[Kerry and I]'ve created [...] a style that defines a new form of music – a kind of anthemic-orchestral-rock-musical-theatre fusion," while Ellis remarked, "I think [Anthems has] got a touch of camp to it, really.

After attending Anthems: The Concert, critic Mark Shenton of The Stage hailed Ellis, a "small but fierce and fiery performer," as "this generation's Elaine Paige, with a similarly soaring, scorching voice."

Among other participants from the London theatre community, Ellis additionally lent her voice to "inspirational" videos that were released upon to video-sharing website YouTube for the "It Gets Better" campaign – a project created by columnist Dan Savage in response to school bullying and a rash of suicides among young LGBT people aiming to "provide hope to youth struggling with their identity.

Ellis returned to her theatrical roots on the New Generation tour of The War of the Worlds, performing the role of Beth, at arenas around Europe from November 2012 to January 2013.

Ellis also performed the role of Mimi alongside Superstar finalist Rory Taylor in the 20th anniversary concert production of the musical RENT that toured the UK, opening on 25 April 2013 at The Opera House in Manchester before playing theatres in London, Liverpool, Newcastle, Cardiff, Birmingham, Stoke-on-Trent, Glasgow and Leeds.

She also appeared on select dates in the musical concert The West End Men led by Lee Mead at London's Vaudeville Theatre from 25 May to 22 June.

Ellis will also perform at A Night at the Musicals when it returns to the Wales Millennium Centre as well as appearing as a special guest in a Christmas Spectacular at the Royal Albert Hall in December.

[90] In the first quarter of 2014, Ellis performed in West End Anthems at the Watford Colosseum and also returned to 20th anniversary concert tour of RENT for dates across the UK in January and February.

On 12 July 2014, Ellis joined Wicked's original Broadway Glinda, Kristin Chenoweth in a duet of "For Good" during her one night only solo concert at the Royal Albert Hall.

[93] On Sunday 27 September, she performed in the previously announced one-night-only concert with fellow West End Star and friend Louise Dearman at the Prince Edward Theatre.