Bowersox and her twin brother, Carl, were born in Elliston, Ohio.She attended Oak Harbor High School in Oak Harbor, Ohio, and later attended the Toledo School for the Arts in Toledo, Ohio.She was in choir and played flute in the school marching band. Bowersox performed her first professional gig at the age of 10. She appeared at local bars in Toledo, most popularly Papa’s Tavern, and The Village Idiot in Maumee, Ohio. At the age of 17, she moved to Chicago looking for opportunity. She most commonly played as a busker at several train stations, including the Washington and Lake Redline stops. She frequented open mics, such as the Uncommon Ground Clark and Grace, and Devon locations. She also played extensively in Chicago’s Lakeview neighborhood. In 2006, the Chicago Department of Cultural Affairs chose Bowersox to represent Chicago folk musicians in the Sister Cities program “Experience Chicago”, held in Birmingham, England. In 2007, Bowersox traveled internationally on an independent small cafe tour, including Memphis, Tennessee, Oaxaca, Mexico, and Ankara and Istanbul, Turkey.
Bowersox auditioned for American Idol in Chicago, Illinois. She sang “Piece of My Heart.” Guest judge Shania Twain commented that she had a “raw, natural talent.”
On March 2, 2010, Bowersox was hospitalized because of complications from type 1 diabetes, forcing a last minute switch in scheduling to give her extra time to recuperate. Bowersox confirmed the illness on the May 19, 2010 results show during an interview with host Ryan Seacrest. The men competed that day instead of the women. She sang the next day and impressed all of the judges.