Earlier today, Sam confirmed that she and boyfriend Paul Knightley had welcomed a son into the world and Billie couldn't be more excited.
Taking to Instagram, Billie - who is mum to one-year-old Nelly - gushed: "I am the proudest sister and auntie in the world @samanthafaiers1 and Paul.
"I cannot describe my love for my beautiful nephew... I love you all so much and I can't wait for all the wonderful time we are going to spend together with him and Nelly."
Billie finished her post with lots of blue heart and baby emojis!
Sam had kept the sex of her baby a secret until the birth and she is still yet to reveal his name.
Meanwhile, many of Sam's co-stars have rushed to congratulate the couple on their new arrival.
Danielle Armstrong tweeted: "Awe it's a boy!!! Congratulations @SamanthaFaiers and Paul on the arrival of your baby boy, lots of love xx."
Lewis Bloor, meanwhile, added: "Big congratulations @SamanthaFaiers on the birth of your baby boy, you will make a wonderful wonderful mother."
Awe it's a Boy!!! Congratulations @SamanthaFaiers and Paul on the arrival of your baby boy lots of love xx— Danielle Armstrong (@Daniarmstrong88) December 30, 2015
And Frankie Essex, sister of Sam's ex-fiancé Joey, said: "Congratulations @SamanthaFaiers on the amazing news, a baby boy x."
Sam's former Celebrity Big Brother co-star Casey Batchelor has also sent her love. She tweeted: Congratulations @SamanthaFaiers and Paul on your beautiful baby boy. I'm sure he is perfect in every way."