The 64-year-old actress explained that she was diagnosed with breast cancer several weeks ago.
Earlier this year, the Harry's Law star revealed that she had successfully battled ovarian cancer nine years ago.
"After much consideration, I underwent a double mastectomy," she told People.
"Luckily, I don't have to undergo radiation or chemo. My family call me Kat because I always land on my feet and thankfully this is no exception."
She added that she remains positive about the future, saying: "My doctors have assured me I'm going to be around for a long time.
"I'm looking forward to getting back to work doing what I love to do."
Kathy Bates is nominated for 'Outstanding Lead Actress in a Drama Series' for Harry's Law and 'Outstanding Guest Actress in a Comedy Series' for Two and a Half Men at this year's Emmy Awards.