Bowersox and Walker plan to wed next month, according to her representative.
The wedding will be the first for Bowersox, who has a 1-year-old son from a previous relationship and split with former boyfriend Tony Kusian the morning before she took the stage with Lee Dewyze for American Idol's final ninth-season performance show on May 25.
While Bowersox initially described her split with Kusian as a "mutual" decision based on his desire to maintain their prior "small town" lifestyle, she later admitted it had surprised her.
"[It] did shock me," she said. "I woke up Tuesday morning and he just had an epiphany. He wanted a simple, quiet life and I respect that. I'm glad he told me instead of sticking it out and realizing it later that he would be unhappy."
The 24-year-old from Toledo, OH signed with 19 Recordings/Jive Records after Idol's finale. Her debut album will be released this fall.