The mother of one wore her Alaïa velvet ruffled dress in the colour burgundy velvet.
Beatrice has only worn this dress once and it was four years ago on a visit to the Portrait Gala in 2019.
The definition of the gown says: “Alaïa’s designs have been worn by some of the world’s best-dressed women, including Naomi Campbell and Michelle Obama.
“Cut from plush burgundy velvet, this fit-and-flare dress is decorated with one of the label’s most recognizable patterns, usually seen on its laser-cut bags and accessories.
“It has a nipped-in waist and tiered ruffles through the skirt that hits just past the knee. Style yours with ankle boots or sandals.”
As Beatrice’s dress is four years old, it is unfortunately no longer in stock so it is unclear how much the garment cost.
The Princess sat behind senior royals like Kate Middleton and King Charles III, so royal fans were unable to see her footwear.
But Beatrice had curled her ginger locks to perfection with a centre parting and also wore dark pink lipstick to perfectly match the burgundy shade of her dress.
Royal fan @claudia_bastante said: “Beatrice looks better than ever. I didn’t like her style very much, but since last year, she’s been rocking it!”
Twitter user @TweetsbyRuth wrote: “Oh wow, I LOVE that dress! I must have it!”
Similarly, @Natnatnat123451 added: “Her style has become so lovely over the last couple of years.
“I used to dislike most of her fashion choices but now I find she looks great in clothes that suit her.”