The former reality star, 67, was able to appear on the show virtually -- as did fellow co-host Eve while Sheryl Underwood and Carie Ann Inaba were in the studio -- and opened up about her granddaughter's illness.
"I was meant to be in the studio, I was so looking forward to it and then, unfortunately, one of my granddaughters has come down with COVID," said Osbourne. "She's OK, she's OK, she's doing good. I don't have it, her daddy [Jack Osbourne] doesn't have it, her mommy doesn't have it, her sisters don't."
The entertainer explained that her granddaughter contracted coronavirus from an employee of Jack's.
"It just goes to show you, she's three years of age, that children can get COVID," stressed Osbourne.
She explained that she has one more week remaining in her quarantine period before she can return to the studio.
"As I say, I don't have it, I keep testing negative, but you have to be safe," she said.
Jack, 34, was "equally upset," his mother said, that he coudln't visit the studio because he hoped to wish Underwood good luck on the upcoming season.
Last month, Osbourne shared a photo of Jack's three girls on Instagram.
"Look who came to stay on our vacay!" she captioned the post, featuring a picture of the trio of girls.