The stars of the ITV daytime show dressed up as The Addams Family to mark the spooky festival, with Alison Hammond as matriarch Morticia, Phillip Schofield as Uncle Fester and Holly Willoughby as daughter Wednesday.
But it was Gibson's appearance as dead pan butler Lurch that won over many viewers, with some struggling to recognise her under her make-up and wig, before her Bristol accent eventually slipped out.
Cara tweeted: "It took me a whole 5 mins to figure out the Lurch was Josie."
Nicky confessed: "It’s just taken me half an hour to realise that’s Josie as Lurch!!!!!"
Missy commented: "Loving @thismorning today. Holly & Philip look awesome. Would love to know who Lurch is."
Debbie said: "I love Josie as Lurch!!! It took me a while to figure out it was her."
And Jilly wrote: "Guys I'm laughing so much who is Lurch ?"
Fashion guru Gok Wan dressed up as son Pugsley, chef Phil Vickery was Grandmama and gadget expert Steve Wilson was Gomez Addams.
Everyone one the show appeared in costume, including Gyles Brandreth, 74, as cousin It, hidden beneath a wig of floor-length.
Yes, I’m at @thismorning evoking a character from the Addams Family for our Hallowe’en special. Jack (on the right) created the ensemble - more Knit than It because the locks are all strands of yarn. pic.twitter.com/qFSinlp0Nt
— Gyles Brandreth (@GylesB1) October 31, 2022
Peter Andre was also a guest on the show under the pseudonym 'Mysterious Ghoul'.
Gibson then burst into song, performing Andre's hit Mysterious Girl.
Willoughby, 41, began the show attempting not to smile and speak in deadpan tones like disturbed child Wednesday Addams.
But she soon abandoned her attempts and became her usual upbeat self.
The show also welcomed the return of guest Brocarde, a 39-year-old singer from Oxfordshire who claims to be in a relationship with a Victoria ghost called Eduardo.
The Addams Family were originally created by cartoonist Charles Addams for the New Yorker in 1938.
It has been adapted into several TV series, including the one starring Carolyn Jones and John Astin in the 1960s, and several film version, including the ones starring Anjelica Huston, Raul Julia and Christina Ricci in the 1990s.
More recently Universal made two animated movies featuring the voices of Oscar Isaac, Charlize Theron and Chloe Grace Moretz, and Netflix is launching TV series Wednesday, starring Catherine Zeta-Jones as Morticia.
Watch: Holly Willoughby and Phillip Schofield booed at the NTAs