Osbourne told Hello! magazine that "I didn't want to live the rest of my life with that shadow hanging over me."
The 60-year-old "America's Got Talent" judge, who had colon cancer a decade ago, said that without the surgery, "the odds are not in my favor."
She added: "It's not 'pity me,' it's a decision I made that's got rid of this weight that I was carrying around."
The magazine went on sale Monday.
Osbourne, husband Ozzy and children Jack and Kelly became rock's most famous clan thanks to reality show "The Osbournes" a decade ago.
Jack Osbourne, 26, was recently diagnosed with multiple sclerosis.