We're pretty sure the photo is of her youngest son, seven-month-old Jett Riviera.
Snuggled up on the sofa, surrounded by cushions, Jett's grabbing one of his toys while a mountain of other play things sits in front of him.
Katie, who has spent her day playing with the little lad, posted the picture on Monday (10 March) and added: "Peek a boo."
She's notoriously shy about sharing pictures of her little one, only posting a few glimpses of her baby son, but this is the second picture we've seen of Jett in just a few days.
And Katie's beady-eyed fans were quick to point out that it is Jett in the snap.
One commented on the picture: "he's massive now I can't believe he's 1 in August there not baby's for long x"
Mum-of-four Katie, 35, gave birth to Jett last summer, after being rushed into hospital while on holiday in Europe with her husband Kieran Hayler.
Celebrities who have welcomed babies in 2014 - pictures!
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe
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