Her best result in singles was reaching the second round in 1928, where she was defeated by fifth-seed and eventual finalist Helen Jacobs.

At the 1930 French Championships, she was unseeded but reached the quarterfinals, where she was defeated by top-seed and eventual champion Helen Wills Moody.

[2] Rost was a singles runner-up at the 1931 German Championships in Hamburg, losing the final in straight sets to defending champion and compatriot Cilly Aussem.

In February 1929, Rost won the singles title at the German Indoor Championships in Bremen after a three-sets win in the final against Ilse Friedleben.

[3] In 1931, she went on a tennis tour to Argentina, Brazil and Chile with Cilly Aussem.