The Princess, 36, the late Queen’s granddaughter, and her property developer husband, 40, revealed the news in a statement from Buckingham Palace. The baby is due early in the new year, according to the statement.
The new arrival will be a sister for Sienna, 3 and Wolfie, 8, Mapelli Mozzi’s son from a previous relationship.
Alongside the announcement the Palace released two new photos, one of the couple hugging and another with Mapelli Mozzi walking with Sienna and Wolfie.

Beatrice, 36, is the ninth-in-line to the throne and the eldest daughter of King Charles’s younger brother Prince Andrew and Sarah, Duchess of York.
The baby will be born 11th in line to the throne, with Beatrice’s younger sister Princess Eugenie moving down to 12th place.
King Charles III has been informed and both families are “delighted”, Buckingham Palace said in the statement.
The couple married in July 2020.
The Duchess of York posted her congratulations on Instagram alongside several photos of herself with her daughter and granddaughter.
“A very proud GiGi/Mum today,” she wrote. “Such an incredible blessing and an embrace to my heart.”
“Wolfie, August, Ernie and Sienna will be over the moon to have the fifth member of the five aside!”