Rebecca revealed the happy news by Tweeting a picture of two swans with a caption about her 'new little gift':
The 27-year-old singer is clearly over-the-moon about the news, as she went on to post a picture of a sonogram along with a sweet poem about how while she is pregnant, she will never be alone.
Rebecca already has two children Lillie May, nine, and Karl, seven, from a previous relationship.
Following a string of unsuccessful romances, most notably with One Direction's Zayn Malik, Rebecca finally found love last year, when she began dating a man who she had known for some time.
Rebecca has so far kept the identity of her partner a secret, but she has described him as "not a bit showbiz."
"He's lovely and he looks after the kids," she said. "He goes fishing with my son."
Speculation about Rebecca's health was stirred up in February when she collapsed during a performance on Loose Women.
At the time Rebecca said she had fainted simply because she had 'nothing left' and she was pushing herself to get through the song. But dizzy spells are common during pregnancy, so perhaps her 'new little gift' had something to do with it?