[2] Fearnley was born Sadie J. around 1885 in Fall River, Massachusetts, the daughter of Joseph and Sarah who immigrated to the United States from England.

[5] After college, Fearnley moved to New York City and began her acting career[6][7] performing both on stage and film until the early 1920's.

[13] By 1913, she had solidified herself as a leading film actress, often starring opposite King Baggot in films such as the Human Hearts, Lady Audrey's Secret and A Cave Man Wooing.

[16] She returned to the stage 1916, touring with a company playing the role of Ruth Goldman in Potash and Perlmutter[16][17] then in the early 1920s as Mrs. Marshall in Irene.

[19] Pearl White lived with Fearnely for a short time around 1913 and traveled to Bermuda together.