The mum-to-be beamed for photographers as she arrived at a star-studded party at London's Saatchi Gallery accompanied by her husband Nick Candy.
She flattered her blossoming baby bump in the form-fitting black and white number and teamed the look with a pair of nude Louboutin pointed heels and a black blazer.
The 30-year-old added some glamorous sparkle with a sequined black Chanel clutch and a dazzling pair of statement earrings.
Her property tycoon husband was suitably dapper for the occasion wearing a slick black three-piece suit and a crisp open white shirt.
News that the former Neighbours star and her husband were expecting a baby emerged when photos of Holly's baby bump were published by Australian magazine Women's Day.
Only a month after their lavish LA wedding, Holly and Nick revealed that were already thinking about starting a family together.
"You have to ask God, but I say we will," the former Strictly Come Dancing contestant told the Telegraph. "It's generally what you do."
"We will have a family, God willing, and when it happens I just want to be a mum," said Holly. "The biggest luxury on the planet to me would be to be at home with my child.
"Finally at 30 I am coming round to the idea of babies and Nick, at 40, is well and truly ready," the Kiss Kiss singer added. "I think he might just get his way. I can see it now: I will be the bad cop – the strict one – and he will be the fabulous, fun dad!"
Speaking exclusively to HELLO!, the couple also said they would consider adopting a child .
"We're leaving pregnancy to fate," said Holly. "I'm from a big family and would like lots of kids - but they don't necessarily all have to be ours."
Holly and Nick married in an extravagant ceremony, attended by Princesses Beatrice and Eugenie, Simon Cowell and Tracy Emin, in September 2012.