The TV star looked sensational in the eye-catching frock that highlighted her endlessly toned legs and tiny waist. The limited-edition number features a round neckline with a pleated opening at the front and back, wide armholes, and a matching fabric belt.
WATCH: Cat Deeley has fun day out with two sons
Cat teamed her thigh-skimming dress with a pair of gold strappy heels and statement burgundy drop earrings. She styled her long blonde hair into a sleek top knot which she joked gave her "a facelift".
Cat shared several behind-the-scenes photos on Instagram ahead of Wednesday's episode and her fans went wild for her bold look.
"Gorgeous! I love blue on you," replied one. A second said: "This was a very chic look." A third added: "Darling the fashion! Stunning fox alert." Many others were lost for words and simply commented with flame and love-struck emojis.
Cat looked incredible in her blue dress
Cat's glam look comes after she joked about spending the last three years in "sweat pants, no makeup and mum buns".
In April, Cat confirmed that she was temporarily moving back to LA with her family for the new season of So You Think You Can Dance, which she has hosted since 2006.
Cat and her family - husband Patrick Kielty and their sons, Milo, six, and James, three - moved back to London at the beginning of the pandemic after living in America for 15 years.
The TV star highlighted her best features
She explained to the Telegraph: "We wanted the boys to go to school here, not because it's better, just because we understand it more. And the biggest thing was to be closer to family.
"You have such a small amount of time when everyone wants to hang out, so we moved back to take advantage of that. And then the pandemic hit…"
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