The television presenter and model said in a three-minute video posted on the website Modernmom.com that she will need her thyroid removed.
"I need to have thyroid surgery and a thyroidectomy, which means I'm going to have a nice, big scar right here on neck," Burke said, drawing a finger across her throat.
Burke, a former winner of ABC's celebrity ballroom dancing competition, said she had a biopsy in July, but it had taken her months to go public with the results.
"I'm ready to deal with it, and I'm going to be fine," she said.
There was no word on when the surgery would take place, but Burke's publicist said her work schedule for "Dancing with the Stars" would not be affected.
Burke, 47, said in July that her doctor suggested she undergo a thyroid ultrasound after he felt a lump in her neck during a routine physical.
The thyroid is a gland in the neck that produces hormones that regulate vital body functions, such as heart rate and blood pressure.
Burke's co-host Tom Bergeron said on Thursday during an appearance on the CBS chat show "The Talk" that he had known about her condition for several months. "We are all there with her," he said.
"I've known about this for a few months ... I have had experience with this in my family. You never want to hear the word cancer. But thyroid cancer is one of the most treatable cancers. It has an incredibly high success rate," he said.
