The 48-year-old DJ revealed that his daughter Jade, 27, is expecting a baby, and he also let slip that her due date is December 29.
Speaking on his BBC Radio 2 breakfast show yesterday (Sunday, June 22), Chris went on to say that he never expected to become a grandfather at such a young age - especially as his youngest son has only just turned two years old.
"My daughter rang to tell me I was going to be a granddad," he told his 9.85 million listeners.
"This now puts me staring straight down the barrel of becoming a granddad at the age of just 48."
Chris walked Jade down the aisle at her wedding to car mechanic Callum last September.
Jade is Chris's daughter from his relationship with his former fiancée Alison Ward. Following a brief marriage to Billie Piper, he is now married to his wife Natasha, and the couple have two sons, Noah, five, and two-year-old Eli.
"Noah is going to become an uncle as well as little Eli, who is just two," added Chris. "And Tash is going to be a grandma."
Chris has previously spoken of his and Natasha's struggle to have a second child, and their joy following successful IVF treatment.
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