The 'Skyscraper' singer showed off her blossoming baby bump in a tight black T-shirt while walking around the theme park in Windsor on Saturday, 12 July.
Sam and husband Craig were pictured walking hand-in-hand with their son Tommy and daughter Brooke as they enjoyed a day in the sunshine.
Among their activities for the day were stops at the Duplo Valley Airport helicopter and the Boating School – where Sam looked like she was having just as much fun as her little ones!
Sam, 37, is expecting her third child in September – and her X Factor mentor Sharon Osbourne has already agreed to be godmother!
On 12 March, Sharon tweeted at Sam: "I would be honoured to be your baby's Godmother!"
@LEGOLANDWindsor had a wonderful day! Kids LOVED the new things to do. Such a great day out!!— Sam Bailey Official (@SamBaileyREAL) July 12, 2014
Sam then replied: "Wow… I am so pleased. Thank you. I am one very lucky lady to have you in my life Mrs O."
She announced her pregnancy in March, revealing she discovered she was expecting after taking a pregnancy test in the toilets of her local supermarket.
Juggling two young children and a pregnancy hasn't slowed the singer down, however, as she's been busy on the promotional trail for album The Power of Love, which hit the number one spot earlier this year.
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Listen to Sam singing 'Skyscraper' below: