The TV presenter posted a photo of herself with her son Chester’s shadow stood next to her, looking up.
“Me and my shadow... 😍” she wrote on Instagram on Wednesday 26 July.
Mums picked up on the fact that the word shadow had a double meaning, referring to kids always following behind wherever they go.
“Yep, I have one of those,” one person wrote. Another commented: “My little girl’s the same always following me about haha.”
Others loved the fact that two-year-old Chester was staring up at Willoughby.
“Capturing a beautiful moment,” one person wrote. “No matter how tall we grow we will always look up to our mothers.”
Another person commented: “Lovely ‘Peter Pan’ moment. That’s the look of love from your son.”
And someone else wrote: “This photo is simply beautiful.”
Willoughby is also mum to seven-year-old Harry and six-year-old Belle with her husband Dan Watkins.