By the time she was 15, Helen was onstage professionally, touring the Orpheum Circuit with the Marx Brothers. Helen spent the early 1920s trouping in vaudeville as a singer, playing the New York Palace for the first time in 1921. Kane was singing the popular song 'Thats My Weakness Now', when she interpolated the scat lyrics 'boop-boop-be-doop'. Four days later, Helen Kane’s name went up in lights. Overnight, the world changed for Helen.
As she took on the status of a singing sensation, there were Helen Kane dolls and Helen Kane look-alike contests, appearances on radio and in nightclubs. In late 1928 and early 1929 this cult following had reached its peak. Helen Kane's height about 5 feet tall and slightly plump figure attracted attention and fans. Her round face with its huge brown eyes was topped by black, curly hair; her voice was a baby squeak with a distinct Bronx accent. Audiences found Helen adorable.
In 1930, Fleischer Studios decided to cash in on Helens popularity. They assigned staff animator Grim Natwick to come up with a girlfriend for Bimbo the Dog. the result was a caricature of Helen Kane, with droopy dog ears and a squeaky singing voice. 'Betty Boop', as the character was dubbed, became an instant smash hit and the star of her own cartoons. By 1932, she became human, her long ears turning into loop earrings.
In 1932, she filed an unsuccessful 250,000 dollar suit against Paramount and Max Fleischer, charging unfair competition and wrongful appropriation in the Betty Boop cartoons. The trial opened in April 1934 with Helen Kane and Betty Boop films being screened by Judge McGoldrick no jury was called. Betty Boop voice-over talent Mae Questel, Margy Hines and Bonnie Poe were brought in to testify. McGoldrick ruled against Helen in 1934, claiming that Kanes testimony could not prove that her singing style was unique or not an imitation itself.