In the spring of 1937 eighteen year old Carole auditioned for director Busby Berkeley. He was impressed with her dancing and her beautiful figure. Busby gave her a small role in Varsity Show, the Warner Brothers musical he was directing. Carole appeared as in a few scenes and was featured in the musical finale. Off screen she started a highly publicized romance with Busby. He was was 23 years older than her and had been married several times. Busby helped Carole get a one year contract at Warner Brothers for $50 a week. Since she was still considered a minor she actually had to got to court to get the contract approved. She was given bit parts in more than a dozen films including Hollywood Hotel, Gold Diggers In Paris, The Patient In Room 18, and Blondes At Work.
Busby encouraged Carole to change her hair from platinum blonde to brunette. He wanted to marry her but his mother did not approve. In 1938 Carole starred in the Warner Brother Academy radio show "Special Agent" and appeared on the cover of Pic magazine. That same year her estranged husband Irving Wheeler decided to sue Busby Berkeley for alienation of affection. He lost the case but the bad publicity hurt Carole's reputation. When her contract expired Warner Brothers did not renew it. Carole's romance with Busby ended in the Summer of 1938. She said "I think Busby is a very grand person and I have the highest regard for him. I do hope someday he'll meet the right person to bring him happiness as a life companion. I wasn't the right person.".