The former TOWIE star made the happy announcement over the bank holiday weekend at her baby shower (Sunday 3 May).
And... it's a boy!
On Sunday morning, Billi teased her fans that she would be announcing the sex of her baby at her party in the afternoon.
She wrote: "Baby Shower. Boy? Or Girl? #BigReveal #BabyCarroll @andytcarroll."
She then posted a picture of herself standing beside a big box adorned with blue and pink hearts.
After a brief countdown, Billi then shared a picture revealing blue balloons floating out of the box!
It's My Baby Shower can't wait to see everyone!— Billi Mucklow (@BilliMucklow) May 3, 2015
Fans rushed to congratulate yoga instructor Billi, with many admiring her gorgeous white maternity dress and the balloon method of announcing the good news.
One fan wrote: "Congrats Billi hope your having a lovely day #boysarethebest."
Billi is fast approaching her due date with footballer fiancé Andy Carroll.
The couple announced they were expecting their first baby together on Christmas Day, and have since kept fans updated on her pregnancy.
During their recent holiday to Abu Dhabi and Dubai, Billi revealed she had reached the 30-week mark in her pregnancy.
That was three weeks ago, so she could only have a few more weeks to go. Eek!
She also confessed she was finding it more and more difficult to keep the baby's sex a secret... But now the secret is out!
Congratulations Billi and Andy.
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Copyright: Twitter @VanessaLachey