She spent most of her life in Gothenburg, Sweden, and much of her fiction is set there. Elkan is best-known for her historical novels "John Hall" (1899), 1904-1906 "Konungen" ("The King", 1904 to 1906), about the Swedish King Gustav IV, "Anckarström" (1910) about the man who killed King Gustav III.

Sophie also wrote short stories and travel books. She was a close friend of and travel companion to Selma Lagerlöf, with whom she was secretly in love. Sophie was the (unsuccessful) rival to Valborg Olander, the lover of Selma Lagerlof.

She is the subject of a 2001 biography, "Sophie Elkan", by Eva Helena Ulvroos. A selection of Selma Lagerlöf's letters to Sophie Elkan were published 1993. She is buried at Gothenburg's Old Jewish Cemetery.