X Factor contestant, 36, shared an Instagram update on Friday to announce the joyous news, posting an adorable snap of their new baby.
Alongside the photo, she penned: 'Surprise! Turns out I can keep a secret. Born on Valentines Day. 'Rebecca, who was a finalist on the competition in 2010, and Jonny kept the pregnancy a secret and have yet to announce the name and gender of the newborn.
The couple married in December of last year at her 'dream wedding venue' in London's upmarket Mayfair district, after seven years of dating.
Speaking at the time, Rebecca said the 'final puzzle piece' in her life is now in place after a ceremony at The Dorchester hotel.
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