She began her career in Broadway theatre, appearing in plays such as The Girl in the Barracks (1899),[2] The Stronger Sex (1908–1909), The Only Law (1909),[3][4][5] Where There's a Will (1910), You Can Never Tell (1915), The Importance of Being Earnest (1921),[6] and Montmartre (1922).

[7] She also appeared in productions of The Wizard of Oz,[8] Babes in Toyland, Father and the Boys (1910),[9] The 'Mind-the-Paint' Girl (1912),[10][11] Nothing But the Truth (1916),[12] and Kissing Time (1921).

"[15] Her stage work was not always so admired; "If Miss Frenyear would not shriek her lines unintelligibly," commented one reviewer in 1915, "the worst defect of the production would be removed.

"[16] In addition to being a stage actress, Frenyear appeared in three silent films; A Fool There Was (1915), a Theda Bara vehicle,[17] Tit for Tat (1915), a comedy,[18] and Social Quicksands (1918),[19] written by Katharine Kavanaugh.

On her first trip to make films in Los Angeles in 1914, she made headlines for criticizing local women's fashion.