The RTÉ show is an annual tradition in many households across the island of Ireland.
As usual, children will be invited to test out the latest toys and give their honest reviews on the show.
And dozens of others from across Northern Ireland and the Republic of Ireland will be showcasing their singing and dancing skills.
Maire said "it was a dream come true to get the phone call" after her mother sent RTÉ a video of her singing.
"I've been singing from I was no age and I just love what it does to me and how others around me react.
"I can't say anything about what I'm doing but I will be singing to millions of people and it's going to be out of this world."
The 16-year-old said she has been watching the Late Late Toy Show from a young age.
"We always get the sugary snacks out and watch all the laughs and performances. I really hope other young girls watch on Friday night and realise dreams can come true if you push yourself in music or dance."
Christmas movies have been a theme since Kielty took over as presenter of the Late Late Show in 2023 and that continues this year with the Dundrum man dressing up as The Grinch.
He has previously impressed audiences with his Elf show in 2023 and Home Alone in 2024, but this year he will need a lot longer in the makeup chair.
Kielty said he'll be spending three hours there, using a combination of cosmetics and prosthetic moulds to transform into the infamous green humbug.
He added that it takes about an hour and a half to remove the look, joking: "Let's see what happens."
"Some would say that there's very, very little transformation required facially for that [the Grinch] to happen," Kielty said.
"So I am very much pushing back on that though."
The opening of this year's show will also feature Ballymena native, Liam Neeson, who has recorded a special voiceover.
The Late Late Toy Show is routinely the most watched television programme in Ireland, reaching well over a million people with its Christmas cheer.
Mr Kielty praised how the show isn't geo-blocked - so it can be enjoyed by viewers from across the world.
"I feel that the show... there is a sort of sense that it's Irish Thanksgiving," he said.
"It's that idea that it's not quite Christmas, but it's got that people coming together feel and wherever you are in the world, you can you can tune-in and be part of it.
"And that's another reason why it's such a special thing to host."
People can watch the show on Friday 5 December at 21:35 GMT on RTÉ One and RTÉ Player.