She was a resident player at Castle Square until September 1911 when she left to tour as Pearl Williams in Karl Hoschna's original musical The Wall Street Girl.

She came to wider attention as The Flapper in the hit play His Majesty Bunker Bean; touring nationally in the role in 1915-1916 and appearing in a lengthy run in Chicago prior to performing the part on Broadway in 1916.

After the success of Bunker Bean, Shirley appeared in numerous Broadway plays and musicals through 1932; including creating the roles of Fanny Welch in Oh, Lady!

[4] Some of the first larger parts Shirley performed at Castle Square included Maria in The School for Scandal (1909),[5] Esther Strong in Denman Thompson and George W. Ryer's Our New Minister (1909),[6] Ione Nuneham in Henry Arthur Jones's The Evangelist (1909),[7] Marie in A Parisian Romance (1909),[8] Mollie Worth in Leo Ditrichstein's All On Account of Eliza (1909),[9] Charyllis in John Stapleton's A Bachelor's Honeymoon (1909),[10] Rose Budd in Charles H. Hoyt's A Contented Woman (1909),[11] and Nami in The Geisha (1909).

[12] The latter role brought her good reviews in The Boston Globe which stated "Miss Florence Shirley is making an emphatic hit at the Castle Square in the character of Nami.

[14] Other roles she portrayed with the company that year included: Edward, Prince of Wales in Richard III,[15] Lulu Bloodgood in Ditrichstein's Are You A Mason?,[16] Dicky in Theodore Burt Sayre's Tom Moore,[17] Rosalie in The Marriage of Kitty,[18] Florence Henderson in Rida Johnson Young's The Boys of Company "B",[19] Trixie Clayton in Brewster's Millions,[20] Nellie Garthorne in J. Hartley Manners and Henry Miller's Zira,[21] Dorothy Tremble in Sydney Grundy and Henry Pettitt's The Bells of Haslemere,[22] Helda in George Broadhurst's The Crown Prince,[23] Violet Lansdowne in Clyde Fitch's Girls,[24] Lily Bell in Edward Peple's The Love Route,[25] Mrs. Denham Lane in Michael Morton's My Wife,[26] and Geraldine Wilcox in George M. Cohan's musical The Talk of New York.

[28] Her 1911 appearances at Castle Square included Osric in Hamlet,[29] Dolly Foulis in Evelyn Greenleaf Sutherland's The Road to Yesterday,[30] Liza in Goethe's Faust,[31] Louka in George Bernard Shaw's Arms and the Man,[32] Jessica in The Merchant of Venice,[33] Dick in Little Lord Fauntleroy,[34] Helen Heyer in The Lottery Man,[35] Josephine Van Dusen in Cecil B. DeMille's The Genius,[36] Lucille Perkins in Edith Ellis's Mary Jane's Pa,[37] Marion Hayste in H.A.

Du Souchet's My Friend From India,[38] Beatriz in David Belasco and Richard Walton Tully's The Rose of the Rancho,[39] and Hope Georgia Langdon in A Gentleman from Mississippi.

[41] She made her debut with the company in the premiere of a new musical by composer Karl Hoschna, The Wall Street Girl, at the Majestic Theatre in Harrisburg, Pennsylvania on October 5, 1911.

[45] The sinking of the Titanic occurred on the same day as her Broadway debut, and she participated in a benefit concert for those impacted by the tragedy later in the week at the George M. Cohan Theatre on April 20, 1912.

[55] In April and May 1913 she was once again at the Castle Square Theatre as Setsu in David Belasco's The Darling of the Gods,[56] Ethel Granger-Simpson in Booth Tarkington's The Man from Home,[57] Constance Neville in Oliver Goldsmith's She Stoops to Conquer,[58] Dorothy Welles in George M. Cohan's Get-Rich-Quick Wallingford,[59] Saide Adams in The Fires of Fate,[60] and Lesbia in The Comedy of Errors.