The ABC program, as always, is at the forefront showcasing the biggest names in pop music on the five and a half hour show, which begins at 8 p.m. EST and for the first time ever will feature countdowns from multiple time zones. Seacrest and co-host Jenny McCarthy will usher in performances by Mariah Carey, DNCE, Gloria Estefan and the cast of the Broadway show, On Your Feet, and Thomas Rhett live in New York City from Times Square.
As well, Fergie will keep the party going at the Billboard Hollywood Party performing two songs of her own while bringing on performances by Alessia Cara, G-Eazy, Bebe Rexha, Martin Garrix, Emeli Sande, Fifth Harmony with Ty Dolla $ign and Kid Ink, Flo Rida with Macy Kate, Hailee Steinfeld, John Legend, Lukas Graham, Mike Posner, Niall Horan and Shawn Mendes.
And Pretty Little Liars star Lucy Hale will make history hosting the first ever Central Time Zone countdown -- complete with the traditional fleur-de-lis drop atop Jax Brewery -- with performances by Jason Derulo and Panic! At the Disco. Demi Lovato -- who performed in Times Square last year -- will bring in 2017 in a much warmer climate streaming live from St. Maarten, and Lionel Richie will perform the very first song of 2017 live from Las Vegas.
"People ask what's going on in the show and the list gets longer and longer," Seacrest said of the broadcast, which will celebrate its 45th Anniversary on the air.
To mark the occasion, Carey will return to Times Square to take the stage just before midnight. The pop icon has the distinction of being the very first entertainer to headline the live performances in Times Square back in 2005. Seacrest, who celebrates his 12th year hosting the show, is excited to reunite with his fellow American Idol alum for the famed countdown.
"Mariah and I were together on Idol, so I have known her and I play her songs a lot especially this time of year," he said. "She owns being Mariah Carey. There is an essence to her... I think I said to her, 'What time do you wake up?' and she said noon. And 'what do you do first?" and she said 'I take a bath' and she has champagne sometimes with it. She's Mariah Carey, the one and only."
McCarthy does have some insight into the performance aspect of New Year's Eve, offered by her husband, Donnie Wahlberg of New Kids on the Block. She said he told her the whole experience is a bit "weird" because you perform facing the camera with the live audience behind you.
As for those in the crowd, they are advised to adhere to stricter safety rules this year, as in no backpacks or umbrellas, and "just your bodies, your coats and that's it," McCarthy said. Additionally, revelers are not permitted to leave items in place of where they are standing, Seacrest added. But one thing they both agree on as a necessity, however, is "adult diapers."
"I stop drinking liquids around 9 a.m. because we don't have bathroom breaks," McCarthy said. "It is literally non-stop."
And after the ball drops, Seacrest has one song request for Richie to play from Las Vegas: "All Night Long."
"That'll be the first song," he said. "It better be!"