Although the reality TV star is more known for commenting on famous people as a couch potato on the C4 series, she briefly stepped into their world on Saturday night (31 October).
Who knew Scarlett and Wossy were even friends?
Twenty-four-year-old Scarlett dressed to kill - literally! - in spooky festive gear when she arrived with her plus one at Jonathan's Hampstead home for his yearly shindig.
Clearly thrilled to have gotten an invite, Scarlett tweeted her 249,000 followers: "Super excited for @wossy Halloween party tonight eeeek I love Halloween #Halloween."
After the celeb-packed bash, Scarlett - who is a disability advisor for students - simply said: "Best night ever."
But we need more details!
Scarlett is famous for her sarcastic and witty TV commentary and has previously revealed that chat show host Jonathan follows her on Twitter.
On the spooky night out, Scarlett mingled with the likes of Leigh Francis, aka Keith Lemon, who dressed as Teenwolf.
The Voice's newest mentor Paloma Faith also attended the event, and looked seriously terrifying.
David Williams paid tribute to The Joker, Gok Wan dressed as an evil clown, while the host himself appeared to be wearing a zombie Indiana Jones outfit!
Other celebs attending included former Girls Aloud star Nicola Roberts, film actor Simon Pegg, reality TV star Ashley James, Sherlock actor Martin Freeman, singer Tinie Tempah and comedian Jimmy Carr.
We have to say, our favourite outfit has to be BGT judge David Walliams' though!
Did you dress up this Halloween? Tell us what you wore in the comment box below!
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