Schell premiered in Steiner's 1942 film "Steibruch", side by side with the well-known Swiss actor Heinrich Gretler, and took acting lessons for several theatre engagements. After World War II, she was cast in her first leading role in the 1948 film "The Angel with the Trumpet", directed by Karl Hartl. She starred in such films as "The Magic Box", "Dr. Holl" (1951), "So Little Time" (1952), "The Heart of the Matter" (1953). Her emotional acting earned her the nickname "Seelchen" ("little soul"), coined by her colleague Oskar Werner.