Taking to her Instagram stories, the Great British Bake Off host posted a selfie with her boyfriend along with the caption "Happy Valentines".
In the picture, Alison and David, who she confirmed she was in a relationship with last May, can be seen beaming at the camera while wearing woolly hats and warm coats.
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The picture marks the first time Alison, who keeps her personal life fairly quiet, has posted David to her socials, making the couple Instagram official.
Alison previously spoke out about the couple's 22-year age gap, describing the relationship between them as a "jigsaw".
Speaking to Good Housekeeping UK, Alison said: "I can see how, on paper, you'd notice the age difference. But honestly, when we see the word 'toyboy' written about us, it bears no relation to what we have at all.
"Yes, I'm 22 years older than he is, but if you saw us together, you'd understand. People have said to me: 'We get it now.' He's so mature and sensible, and I'm so not.
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"And the things he says to me... they're just so lovely. It's like a jigsaw: we fit and it all comes together."
The presenter previously denied engagement rumours after she was spotted wearing a sparkling ring while presenting This Morning.
After her co-host Dermot O'Leary pointed out that the ring was on her wedding finger, Alison said: "It's just some cheap ring that I got from, probably Primark, one of those cheap rings. It's nice, isn't it?
"Let me swap it over, because we don't want those rumours going out there, do you know what I mean? Not just yet. Maybe one day, who knows."