She was born Eleonore Nest on August 4, 1915, in Berlin to American parents who were Methodist missionaries. During her parents' time as missionaries, she was discovered by a German movie producer on a poster promoting a Sunday school program. She was soon asked to work in movies. With the permission of her parents, she acted in her first movie in 1918. She used the name Loni Nest instead of Eleonore Nest. Between 1918 and 1933, she starred in 41 movies, opposite such actors as Charles Boyer, Greta Garbo, Marlene Dietrich and Fritz Feld.