In 1936, she left the endurance contests, determined to become a professional singer. She started out as a chorus girl in such Uptown venues as the Celebrity Club and the Vanity Fair, and then found work as a singer and waitress at the Ball of Fire, the Vialago, and the Planet Mars. At the Vialago, O'Day met the drummer Don Carter, who introduced her to music theory; they wed in 1937. Her first big break came in 1938 when DownBeat editor Carl Cons hired her to work at his new club at 222 North State Street, the Off-Beat, which became a popular hangout for musicians. Also performing at the Off-Beat was the Max Miller Quartet, which backed O'Day for the first ten days of her stay there. While performing at the Off Beat, she met Gene Krupa, who promised to call her if Irene Daye, then his vocalist, ever left his band. In 1939, O'Day was hired as vocalist for Miller's Quartet, which had a stay at the Three Deuces club in Chicago.
In 1936, she left the endurance contests, determined to become a professional singer. She started out as a chorus girl in such Uptown venues as the Celebrity Club and the Vanity Fair, and then found work as a singer and waitress at the Ball of Fire the Vialago, and the Planet Mars. At the Vialago, O'Day met the drummer Don Carter, who introduced her to music theory; they wed in 1937. Her first big break came in 1938 when DownBeat editor Carl Cons hired her to work at his new club at 222 North State Street, the Off-Beat, which became a popular hangout for musicians. Also performing at the Off-Beat was the Max Miller Quartet, which backed O'Day for the first ten days of her stay there. While performing at the Off Beat, she met Gene Krupa who promised to call her if Irene Daye, then his vocalist, ever left his band. In 1939, O'Day was hired as vocalist for Miller's Quartet, which had a stay at the Three Deuces club in Chicago.