The daughter of the producer and playwright Robert Courtneidge, she was appearing in his productions in the West End by the age of 16, and was quickly promoted from minor to major roles in his Edwardian musical comedies.

Courtneidge, the elder daughter and second of three children, was born in Sydney to a theatrical family,[1] while her father was touring Australia with the J. C. Williamson company.

Her parents were the Scottish producer and actor Robert Courtneidge and his wife, Rosaline May (née Adams), who worked under the stage name Rosie Nott.

[2] In 1901, at the age of eight, Courtneidge made her stage debut as the fairy Peaseblossom in her father's production of A Midsummer Night's Dream at the Prince's Theatre, Manchester.

Her London West End debut was at the Apollo Theatre in the comic opera Tom Jones (1907), which had a libretto co-written by her father.

[2][n 2] In the piece that followed, The Mousmé (1911), which also featured a book co-written by her father, she was cast in one of the two leading female roles alongside Florence Smithson.

[2] Reviewing The Mousmé, The Observer wrote that the co-authors had "failed to supply any adequate dramatic raison d'être for the prominent character of Miyo, a fair-haired Japanese damsel, embodied by Miss Cicely Courtneidge with much sprightliness but far too much effort, facial and otherwise, of coy significance.

[2] Also in the cast, in the role of Robert Jaffray, was the 21-year-old Jack Hulbert, making his professional debut after success as an amateur while a Cambridge undergraduate.

The piece was a hit for Courtneidge and her father, playing to full houses at the Shaftesbury Theatre until Britain and Germany went to war in August 1914; anti-German sentiment brought the run to an abrupt halt.

[12] After an early variety engagement in Manchester, the critic of The Manchester Guardian wrote of her "pleasant voice and much charm of manner" in sketches and songs: "one may express a preference for Miss Courtneidge as the hospital sister, presented with all the bright graciousness which properly belongs to the character, over her more elaborate representation of the Flying Corps 'knut'.

[2] Their first revue was Ring Up, by Eric Blore and Ivy St. Helier, at the Royalty Theatre in 1921; they received good notices, but the material was weak, and the show was not a great success.

"[n 4] These shows played in the West End and on tour in the UK, and in 1925 the Hulberts made their Broadway debut in their current revue, By-the-Way.

[17] The fourth in the series, Clowns in Clover, contained one of Courtneidge's most celebrated sketches, "Double Damask", by Dion Titheradge, in which her character, Mrs. Spooner, and two shop assistants become entangled in tongue-twisters.

[2] To achieve this, he and Courtneidge temporarily went their separate professional ways, reasoning that they could earn more as individual stars than as a double act.

[23] Courtneidge did not return to the theatre until October 1937, playing the dual roles of Mabel and her daughter Sally in the musical Hide and Seek, co-starring with Bobby Howes, produced by Hulbert.

In 1941, she presented a nightly three-hour show, raising funds, and then formed a small company which she took to Gibraltar, Malta, north Africa, and Italy, performing for the services and hospitals.

[27] Together with other prominent performers including Robert Donat and Florence Desmond, Courtneidge led professional opposition to a wartime proposal to allow theatres to open on Sundays.

The Australian Quarterly wrote: Cicely Courtneidge radiates the authentic glitter of Shaftesbury Avenue; she brings genuine starshine to Castlereagh Street.

She knows all the tricks in the trouper's basket, and she rings the changes from dry humour to dewy sentiment, from song to dance, from pathos to Hungarian hotcha, and from all moods to subtle mimicry as quick as a naughty wink.

In 1962, she gave what she considered her finest film performance, in a role wholly unlike her usual parts; in The L-Shaped Room she played an elderly lesbian, living in a drab London flat with her cat, recalling her career as an actress and forlornly trying to keep in touch with former friends.

"[39] The last London production in which the Hulberts appeared together was a well-reviewed revival of Dear Octopus at the Haymarket Theatre in 1967 with Richard Todd, Joyce Carey and Ursula Howells.

[41] In 1969, Courtneidge turned to television, playing a working-class role as "Mum" in the first series of the LWT comedy On the Buses, opposite Reg Varney.

[43] Courtneidge's theatre work in the 1970s included tours of Agatha Christie's The Hollow and Peter Coke's Breath of Spring, both with Hulbert.

[44] In 1971, Courtneidge starred in the farce Move Over, Mrs Markham at the Vaudeville Theatre, playing "a prudish authoress from Norfolk, bemused by all the flying exits, unexpected entrances, and atmosphere of incipient carnality.

[47] One of her last appearances was in a royal gala performance at the Chichester Festival Theatre in June 1977, celebrating the Queen's Silver Jubilee.