"As soon as I found out I had the breast cancer gene, I thought, 'The odds are not in my favor,'" Osbourne, 60, told Britain's Hello! magazine. "I decided to just take everything off."
Osbourne's publicist told People.com "The Talk" co-host underwent the 13-hour operation last summer.
"For me, it wasn't a big decision," she told Hello! "I want to be around for a long time and be a grandmother to Pearl. ... It's not 'pity me.'"
Pearl is her son Jack's 6-month-old daughter.
McPhee, Cokas 'working on their marriage' after affair
Beautician charged with giving client fatal silicone butt injection