Eagels left school early and worked at small jobs until, at age 15, she began to work in a traveling tent show. During the next seven years she toured the Midwest, playing mainly melodramatic roles. Gradually she began receiving bit parts in legitimate theatrical productions. More substantial roles came in the touring production of The Outcast in 1915–16, opposite George Arliss (Arliss, George) in a touring company of Disraeli and later in The Professor's Love Story (1917), and in David Belasco (Belasco, David)'s Daddies (1918).

A woman of driving ambition, Eagels achieved fame in a single role, that of Sadie Thompson in Rain, an adaptation of a Somerset Maugham (Maugham, W. Somerset) story that opened in November 1922 and played for four years, nearly 1,500 performances. During that production, in 1925, she married (divorced 1928). Eagels's last stage role was in Her Cardboard Lover. Soon thereafter she turned to motion pictures and vaudeville. She had earlier made Man, Woman and Sin (1927), a silent film with John Gilbert. She also appeared in Jealousy and The Letter (both 1929). Although hampered professionally by health problems and lack of training and personally by an unstable temperament, she was an actress of great potential power, as Rain had demonstrated. She died of a self-administered sedative overdose following eye surgery.