The 54-year-old actor revealed the happy news to US Weekly on Sunday evening, while attending the Mario Batali Foundation Dinner in New York with his pregnant wife.
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Stanley Tucci proudly posed with his pregnant wife, Felicity Blunt, at Sunday's event
"I'm very excited to be a dad. It's incredible," the delighted star said. "I'm most excited to have a baby with Felicity and for the baby to be healthy."
Asked what sort of mother he thought Felicity would be, he sweetly replied, "A great one!"
The parents-to-be happily posed together on the red carpet, Felicity's baby bump visible beneath her grey wrap dress.
The new arrival will be a little playmate for Hazel Krasinski – the eight-month-old daughter of Felicity's sister Emily Blunt and her husband John Krasinski.
Stanley Tucci and Felicity Blunt have been happily married since 2012
It was Emily who first introduced Stanley to literary agent Felicity during filming for The Devil Wears Prada.
In August 2012, Stanley revealed in an interview that the couple had secretly tied the knot – and one month later, they celebrated with a ceremony in London, which was attended by stars including Emily and John, Steve Buscemi, Colin Firth, Ewan MacGregor and Meryl Streep.
This is the first child for Felicity. Stanley is already a father-of-three from his marriage to his late wife Kate, who passed away from breast cancer in 2009.