The former prison officer - nicknamed Screwbo on the show - says she found out after doing a pregnancy test during a trip to the supermarket with her husband.
She told The Sun: “I went and did it in the toilet while he was getting all the food.
“I came out and went, ‘Yep — I’m pregnant’. It wasn’t planned.”
It will be the 36-year-old's third child with hubby Craig, although she admits the news initially left her shocked and upset.
"But they were really good about it. I was going to go on tour solo at the end of October — but I have managed to move it until January.”
But Sam - who is ten weeks pregnant — says she and Craig couldn't be happier that she is expecting again.
“He thinks it’s a New Year’s Eve baby and he could be right. I’ve always wanted three kids.”
Sam has since taken to Twitter to confirm the news, posting a snap of her first scan, which she captioned: 'Meet Peanut!!'
Hey everyone...... Meet peanut!!! :-) pic.twitter.com/QuUzO6yNaj
— Sam Bailey Official (@SamBaileyREAL) March 6, 2014
Congrats to them both!
Who's the mumma? Kim Kardashian Who's the daddy? Kanye West Baby ETA: Next year Interesting fact: Kim's difficulty conceiving the couple's second child was chronicled in 'Keeping Up With The Kardashians', before confirming she was pregnant with a son.
Who's the mumma? Coleen Rooney Who's the daddy? Wayne Rooney. Maybe you've heard of him. Baby ETA: January Interesting fact: This will be the third child for the happy couple.
Who's the mumma? Sam Faiers Who's the daddy? Baby ETA: Early 2016 Interesting fact: Sam confirmed her baby news on Instagram.
Who's the mumma? Keira Knightley Who's the daddy? James Righton Baby ETA: Spring 2015 Interesting fact: Keira and James tied the knot in May 2013. This will be their first baby.
Who's the mumma? Katherine Jenkins Who's the daddy? Andrew Levitas Baby ETA: Late 2015 Interesting fact: The couple shared their baby joy with an adorable snap on Instagram of a pair of pink shoes.
Who's the mumma? Olivia Colman Who's the daddy? Ed Sinclair Baby ETA: Summer 2015 Interesting fact: The 'Broadchurch' actress has two children already with her writer husband, Ed.
Who's the mumma? Katie Halil Who's the daddy? Howard Donald Baby ETA: Early 2016 Interesting fact: This will be the first couple for the couple, who married secretly earlier this year.
Who's the mumma? Kelly Clarkson Who's the daddy? Brendan Blackstock Baby ETA: Early 2016 Interesting fact: Kelly confirmed her baby news in a typically Kelly Clarkson-esque fashion, by claiming she was "totally pregnant" during a live show.