Holly, 38, first slipped into a stunning black strapless Peter Langner gown which was embroidered with a silver and glittery pattern.
She shared a snap to Instagram and wrote: "It’s the most wonderful time of the year... @dancingonice time!"
An hour later, Holly changed her outfit and opted for a glamorous light pink gown.
The Iris Serban strapless number featured a sweetheart neckline and she wore a matching pink shawl over her shoulders.
Holly captioned the post: "A night of 2 dresses..."
Fans gushed over the looks, with one person commenting: "Wow beautiful Holly."
View this post on Instagram
Another wrote: "Wow absolutely beautiful," while a third added: "Oh wow look at that dress."
During the press launch on Monday evening, Holly became emotional as she discussed her relationship with co-star Phil.
You couldn’t do the amount of hours of TV that we do with each other without getting on.
She said: "Phil and I met on this show. There’s a lot of history. You’re going to set me off," as she began getting emotional.
"My kids really love the show as well. I get quite emotional thinking about it, that all of them were carried in my tummy on this show and when we finished I always went off and had the babies.
"So now it’s really nice because they love it and I tend to split it, I bring one of them each week, they come for the whole day and sit through the rehearsals. It’s really nice. It’s a real family show."
In a separate interview with BBC's Newsbeat, the pair hit back at suggestions of a rift after it was claimed that their relationship has become "strained in recent months" - something ITV recently denied.
Holly said: "You couldn’t do the amount of hours of TV that we do with each other without getting on."
Phil added: "We have such a laugh. We’re best mates, she’s like the sister I never had. I just adore working with her, she’s just perfect."
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