He became a member of the NSFP in 1924, which served as a legal front for the Nazi Party when it was banned after the Beer Hall Putsch. The NSFP was reabsorbed into the NSDAP in 1926 after the latter was made legal again, and by 1931 Helldorff had joined the SA, functioning as an SA leader in Berlin. The scope of his work got bigger in 1933 when he was also given responsibility for the SS's Berlin-Brandenburg leadership.