Royle was born in New York City to playwright Edwin Milton Royle and actress Selena Fetter (April 12, 1860 - May 10, 1955). She had an older sister, Josephine Fetter Royle (1901–1992).
Her mother recounted in a newspaper article that she used to take Selena along with her to her rehearsals and performances. One night, then seven-year-old Selena went missing. While the mother frantically searched for her, holding up act two, the audience became restless. The youngster finally turned up - she had gone on stage dressed in her mother's second-act costume; she made a bow, much to the audience's amusement. She later remarked, "And that is the first time I was ever on stage, and I liked it so well I stayed."
She turned to acting despite the objections of her parents. Nonetheless, her father wrote the 1921 Broadway play Lancelot and Elaine to provide both her and sister Josephine with their first professional roles, as Guinevere and Elaine respectively. Eventually, she landed a part on her own in the 1923 Theatre Guild production of Peer Gynt, with Joseph Schildkraut, and became a respected Broadway actress. She made one film in the 1930s, Misleading Lady, but otherwise worked on the stage and on radio.
Royle began her radio career in 1926 or 1927 and performed "almost continuously since", according to a 1939 newspaper item. Her body of work includes playing the title role in Hilda Hope, M.D. She also played Martha Jackson in Woman of Courage, Mrs. Allen in Against the Storm, Joan in The O'Neills, and Mrs. Gardner in Betty and Bob, and was in Kate Hopkins.
In the 1940s, she returned to film and had a successful run, mainly playing maternal characters such as the mother of The Fighting Sullivans (1944) and the title character's mother opposite Ingrid Bergman as Joan of Arc (1948). She also made several appearances on early television. However, in 1951, when she refused to testify about her alleged Communist sympathies before the House Un-American Activities Committee, her acting career came to a sudden standstill. She appeared in only two more films afterwards, including the low-budget Robot Monster (1953).
She was also an author. She wrote several books, including Guadalajara: as I Know It, Live It, Love It (which went through several editions) and a couple of cookbooks, and some magazine articles. She was the "radio editor" of the short-lived New York periodical Swank.
Her first husband was Earle Larrimore, a cousin of actress Laura Hope Crews. They married in 1932 and divorced in 1942. She was married to actor Georges Renavent from 1948 until his death in 1969.
Royle died in Guadalajara, Jalisco, Mexico, on April 23, 1983, aged 78.