The husband and wife team were presenting a piece to camera when Demi stuck her head in from behind to join the shot.
We're pretty sure Rochelle and Marvin won't mind!
Rochelle's fans were pretty amused by the photo she posted to Instagram. One wrote: "Haha, you can't trust nobody these days." Another said: "Omg, this made me lol so much!"
Demi was on the ITV show to perform her new track 'Neon Lights' and join Rochelle and Marvin for a chat on the sofa.
She's in the UK to promote her music and for a couple of performances: one at G-A-Y at the weekend, and a concert at London's Koko club.
Demi also teased a return to the UK in the near future: "I can't say much but I will say I'll be back very soon."
While on our shores she also managed to finally meet up with The Vamps – after already recording and shooting a music video for their collaboration 'Somebody To You'.
"I didn't actually meet them until after I got to the UK this week. I met them and I'd already recorded the song and shot a music video without meeting them! They are really nice."
Demi also spoke about life on the road, saying she does miss her loved ones when she's on tour – so she flies them out to join her.
"It's difficult to not necessarily stay in touch, but I miss them a lot. So, what I do is… my mum is here today and so is my best friend Marrisa. When I don't get to see them I bring them with me!"
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