She began her career in 1908 as a member of the opera chorus in Oscar Hammerstein I's Manhattan Opera Company (MOC). Impressed with Gentle's talents, Hammerstein began casting her in secondary roles in MOC productions in 1909, beginning with the role of Mercédès in Georges Bizet's Carmen. She sang roles with the MOC and with Hammerstein's Philadelphia Opera Company through 1910; including Emilia in Otello, the First maid in Elektra, Flora in La traviata, Lola in Cavalleria rusticana, Maddalena in Rigoletto, Nicklausse in The Tales of Hoffmann, and Siébel in Faust among others.
In 1916 Gentle portrayed the role of Federico in Ambroise Thomas's Mignon at La Scala in Milan. She sang one season at the Metropolitan Opera, making her debut with the company in 1918 as Preziosilla in La forza del destino. Later that year she created the role of Frugola in the world premiere of Puccini's Il Tabarro. Her only other role at the Met was Fatima in Oberon in 1919. In 1923 she toured the United States as Carmen with the San Carlo Opera Company. She appeared in three films during the early 1930s: The Song of the Flame (1930), Golden Dawn (1930), and Flying Down to Rio (1933). In 1940 she made her final stage appearance at the Los Angeles Civic Light Opera as Mrs. Cripps in H.M.S. Pinafore.
- "Alice Gentle Dies. Ex-Opera Star, 69. Mezzo Sang With La Scala and the Metropolitan. Started in Chorus". The New York Times. March 2, 1958.
- Free Library of Philadelphia: Folder: Philadelphia Opera Company 1908-1910