Thom and Jessica each sported black outfits, with former rugby player and model Thom choosing a t-shirt and jeans combination, as well as a leather jacket and 90210 star Jessica opting for a a peplum dress and ankle boots.
Canadian actress Jessica accessorised her outfit with a glittering statement necklace.
Hosted at the Sanctum Soho hotel in London, Heidi's party had an '80s theme that encouraged bold and colourful costumes.
"Hair done," tweeted Liverpool-born Heidi with a photo of her unusual up-do. "Can you guess who I am? X." Birthday girl Heidi then posted several photos on Twitter, showing off her Princess Leia outfit and he sister Hayley's Wonder Woman costume.
Former Eastenders star Tamzin Outwaite dressed as Superman and Heidi's band mate Jade Ewan acknowledged the theme by going as Hilary Banks from Will Smith's '80s TV show, The Fresh Prince of Bel Air.
"It's getting light," tweeted Heidi as her celebrations drew to a close. "The birds are tweeting, had the best time at my party tonight. Good night or good morning tweeties x."
Heidi, Thom and Jessica had also joined forces on Thursday night as they attended the F&F A/W 2013 Collection Showcase at Somerset House. Keeping to the evening's black and white theme, Thom and Jessica sported colour-coordinating outfits with the white lapels on Thom's jacket matching the white panel on Jessica's bodycon dress.
Heidi opted for a white, short-sleeved dress and black heels, adding a splash of colour with a bright red lipstick.
Thom and Jessica confirmed their relationship back in April by posting photos from their trip to music festival Coachella. Thom, who announced his separation from long-term girlfriend Kelly Brook in February, caused a stir just before the festival by tweeting a photo of Jessica giving him a kiss on the cheek before Jessica put an end to weeks of speculation by releasing a photo of the couple kissing on Instagram.
Since then the couple have stepped out together at numerous events and the handsome rugby star was proud to have his lady on his arm when they attended a gala for luxury motoring company Aston Martin on Wednesday.