The 21-year-old, who donned a gold-printed dress and recently said "I do" to fellow YouTube sensation Jake Paul, said her new friend and "queen" Lucy -- the Boa constrictor -- was her "date" on Monday night.
"She's super happy to be here; we're just chilling," Mongeau told Fox News on the carpet.
Lucy was accompanied by a snake handler as the pair did several interviews and posed for photos with fans.
"The snake company that I'm working with, all of the proceeds and the money that they earn goes to rescuing a lot of snakes, especially out here on the East Coast," she added. "It's really cool and I'm super excited to be working with them."
Meanwhile, musician H.E.R. also paid homage to Britney Spears' legendary reptile moment with a snake wrapped around her shoulders. Spears iconically performed “I’m a Slave 4 U” with a python at the 2001 VMAs.
Bringing a live animal to a red carpet caused a stir on social media, with mixed reactions from users.
"Live Animals Are Not Accessories," wrote one user.
"Animals aren’t fashion accessories," said another.
"I swear to god y’all need to stop... animals are LIVING CREATURES not handbags or accessories," added someone else.
A concerned fan posted, "POOR SNAKE. Put it back and leave it alone. This thing will probably die from the stress it experienced! People are so stupiddddd."
And PETA even reacted to the red carpet photos: "Animals aren’t jewelry or accessories–& dead or alive should not be worn on the red carpet. Snakes may not display stress & discomfort as obviously as other species do–they don’t whine or flinch the way a dog might–but constant handling leaves them prone to illness & injury."
"These snakes should be exploring lush jungles & swamps & experiencing all the pleasures they’re so keenly attuned to, not being treated as living props & put through the stress of travel, confinement, confusing conditions, bright lights, & loud noises, all for a cheap photo opp."
"PETA hopes celebrities take notice of the backlash from fans and make compassionate fashion choices in [the] future."